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High entropy alloys (HEAs) challenge conventional alloy design by incorporating five or more principal elements in near-equal atomic proportions, forming random solid solutions with simple phases. HEAs exhibit exceptional properties such as high phase stability, mechanical strength, corrosion, oxidation, wear, fatigue resistance, and notable thermal stability. While traditional methods like arc melting and casting are often used for HEA preparation, they pose limitations due to cost and processing challenges. Additive manufacturing has emerged as a transformative technique, enabling the cost-effective fabrication of complex structures with customized properties. Here, we summarized the following "state-of-the-art" additively manufactured alloy systems: AlCrCoNiX (X = Fe, Si, Ti, etc.) HEAs, CoCrFeMnNi HEAs, and refractory HEAs. This review focused on elucidating their oxidation properties, emphasizing key findings, challenges, and opportunities. It also discussed the potential strategies for enhancing oxidation resistance. Additionally, it highlighted research gaps and underscored the urgent need for further exploration to meet the demands for high-temperature applications. [ABSTRACT FROM AUTHOR]

Pt-Pd-based noble metal catalysts are widely used in engine exhaust aftertreatment because of their better carbon soot oxidation performance. At present, the synergistic effect of Pt and Pd in CDPFs, which is the most widely used and common doping method, in catalyzing the combustion of carbon smoke has not been reported, and it is not possible to give an optimal doping ratio of Pt and Pd. This paper investigates the carbon soot oxidation performance of different Pt/Pd ratios (Pt/Pd = 1:0, 10:1, 5:1, 1:1) based on physicochemical characterization and particle combustion kinetics calculations, aiming to reveal the Pt-Pd synergistic effect and its carbon soot oxidation law. The results show that Pt-based catalysts doped with Pd can improve the catalyst dispersion, significantly increase the specific surface area, and reduce the activation energy and reaction temperature of carbon soot reactions, but excessive doping of Pd leads to the enhancement of the catalyst agglomeration effect, a decrease in the specific surface area, and an increase in the activation energy and reaction temperature of the carbon soot reaction. The specific surface area and pore capacity of the catalyst are the largest, and the activation energy of particle oxidation and the pre-exponential factor are the smallest (203.44 kJ∙mol−1 and 6.31 × 107, respectively), which are 19.29 kJ∙mol−1 and 4.95 × 108 lower than those of pure carbon soot; meanwhile, the starting and final combustion temperatures of carbon soot (T10 and T90) are the lowest at 585.8 °C and 679.4 °C, respectively, which are 22.1 °C and 20.9 °C lower than those of pure carbon soot. [ABSTRACT FROM AUTHOR]

Thermo-resistant nanoalloys are a new class of materials that combine high-temperature refractory compounds (such as carbides, nitrides, borides, and oxides) with nanoscale particles of metals, ceramics, or carbon. These composites exhibit remarkable thermal stability and anti-ablation/oxidation properties, making them highly attractive for various high-temperature applications in aerospace, energy, and high-temperature manufacturing. Despite their potential, the fabrication of these materials is challenging due to their complex synthesis and processing. Many researchers have summarized the challenges and suggested solutions to produce high-density, superior physicochemical properties of nano refractory materials for specific applications. Thus, in view of these perspectives, the present review provides an overview of the production criteria, processing, and synthetic routes for producing high-temperature nano refractory material composites with exceptional thermal and anti-ablation/oxidation properties. The review also highlights the challenges encountered by researchers and their solutions for fabricating these materials. Potential applications of high temperature refractory materials are found in various industries, such as refractory ceramics, high-temperature components in wear resistant, neutron shielding, and high power-density microelectronics manufacturing to name a few.

The effect of Cu content on the high temperature oxidation properties of the phase change material (PCM) Al-Cu-Si alloys was studied. The oxidation kinetics curves at 600℃ were achieved for Al-Cu-Si alloys with 35–55% Cu, which all follow the cubic law. With an increase in the Cu content from 35 to 55%, the weight gain decreases from 5.75 to 3 × 10−4 g/cm2 after 96 h isothermal oxidation. The oxidation rate also decreases with Cu content, the maximum and minimum rates are 1.52 and 0.32×10−5 g/cm2•h, a nearly 4 times difference. Oxidation does not change the phase composition of Al-Cu-Si alloys, but coarsens the microstructure. The latent heat and the starting temperature of phase change after 96 h oxidation at 600℃ have variations of less than 10% and 6℃, respectively, indicating that the Al-Cu-Si alloys have good thermal stability after high temperature oxidation.

Although pinane has a wide range of uses, there are no reports on the safety of pinane oxidation. The thermal oxidation properties of pinane were investigated through MCPVT. The primary oxidation products of pinane were separated and structurally characterised, and its decomposition properties were assessed by MCPVT and DSC. The results showed that pinane had an initial oxygen uptake temperature of 123.5 °C and exploded when the temperature rose to 132.7 °C. Pinane autoxidised at 110 °C for 9 h formed a high level of peroxide (81.18 mmol/kg) with an activation energy of 138.77 kJ/mol. The oxidation of pinane occurs mainly at the tertiary carbon atom attached to the methyl group, and the main peroxide produced is pinane hydroperoxide (PHP). PHP has an exothermic onset temperature (Tonset), a heat of decomposition (QDSC) and an activation energy of decomposition of 114.6 °C, 1878.0 J/g and 109.4 kJ/mol respectively, which should classify it as a hazardous substance. PHP has a lower activation energy than pinane and is the determining factor for the safety of the pinane oxidation reaction. The products of thermal runaway of pinane are relatively complex and consist mainly of 1-(2, 2-dimethyl-3-ethylcyclobutyl) ethanone, nopinone, 2, 3-pinanediol and pinonic acid.

Oxidation is an inevitable problem and accelerates the wear of materials under high temperature wear conditions. To enhance the oxidation resistance of TiC particle–reinforced steel matrix composites (TiC-SMCs), the role of Cr on the oxidation mechanism of TiC-SMCs at 600 °C was investigated through experimentation and first-principles calculations in this work. The results indicated that the addition of 3 wt% Cr could induce a transformation from internal oxidation to external oxidation because the diffusion energy barrier of O atoms was increased from 0.66 to 0.91 eV. Furthermore, The adsorption of the Fe and O atoms was reduced via Cr addition. Consequently, the oxidation resistance of TiC-SMCs was improved and internal oxidation was inhibited with increasing Cr content, where the oxidation rate coefficients of TiC-SMCs with 3 wt% and 0.3 wt% Cr content were 3.79 × 10−4 and 4.84 × 10−1 mg2 cm−4 h−1, respectively. The present study would not only provide the basic understanding for the role of Cr on oxidation behavior, but also contribute to the design of TiC reinforced steel matrix composites with excellent oxidation resistance. [ABSTRACT FROM AUTHOR]

The effects of Ca addition on the microstructure and oxidation properties of a new Mg alloy were studied. The oxidation behavior of the alloys was analyzed by thermal analysis and material characterization of the alloys exposed in flame environment; and both electrical and induction furnaces. Moreover, the surface layers were characterized using field emission scanning electron microscopy, and X-ray diffraction technique. It was found that increasing the Ca addition reduces the grain size and increases the fraction of the secondary phases, and enhances the mechanical properties. Moreover, increasing the Ca contents resulted in the formation of a dense CaO/MgO layer on the surface prohibited the oxygen diffusion and assisted in protection of the substrate against further oxidation. Therefore, ignition temperature was increased from 680 °C to 890 °C after addition of the Ca element. The mechanical properties and ignition behavior of the current materials was compared with the literature which it showed an excellent combination of the properties in the developed alloys.

Severe intermediate-temperature embrittlement as well as rapid softening and oxidation at high temperatures are significant problems for high-entropy alloys (HEAs) in polycrystalline structures, which greatly limit their applications in modern industries. In this study, a novel Co-rich single-crystal high-entropy alloy (HEA), Co41Ni35Al11·5Ta2·5Cr4Ti6 (at.%), was innovatively developed. After isothermally aged at 1250 °C, this alloy exhibits an ultrahigh volume fraction of cuboidal L12-type nanoprecipitates (∼80%) which is higher than those of previous Co-based superalloys. More importantly, the present HEA shows excellent mechanical performance at both ambient and elevated temperatures, and no intermediate temperature embrittlement and rapid softening were observed. Noticeably, the yield strength can still maintain at ∼800 and ∼500 MPa when tested at 900 and 1000 °C, which are superior to other conventional single-crystal alloys. Moreover, extraordinary oxidation resistance can be achieved at the high temperature of 1000 °C due to the formation of a compact sandwich-structured oxide layer.

The effects of Ca addition on the microstructure and oxidation properties of a new Mg alloy were studied. The oxidation behavior of the alloys was analyzed by thermal analysis and material characterization of the alloys exposed in flame environment; and both electrical and induction furnaces. Moreover, the surface layers were characterized using field emission scanning electron microscopy, and X-ray diffraction technique. It was found that increasing the Ca addition reduces the grain size and increases the fraction of the secondary phases, and enhances the mechanical properties. Moreover, increasing the Ca contents resulted in the formation of a dense CaO/MgO layer on the surface prohibited the oxygen diffusion and assisted in protection of the substrate against further oxidation. Therefore, ignition temperature was increased from 680 °C to 890 °C after addition of the Ca element. The mechanical properties and ignition behavior of the current materials was compared with the literature which it showed an excellent combination of the properties in the developed alloys. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the physical stability, oxidation, digestibility and β-carotene sustained-release properties of Pickering emulsions stabilized by rapeseed protein (RP) complexed with chitosan (CS). The results showed that adding CS to RP decreased the RP mean particle size from 3575.0 to 130.9 nm, increased its zeta-potential from 29.6 to 41.4 mV, changed its tertiary structure, and enabled its uniform dispersion. Additionally, CS addition improved RP interfacial properties at air/water and oil/water interfaces, thereby enhancing its emulsification activity and stability. Rheological property analysis exhibited that RP/CS complex had a smaller storage modulus (G′) and loss modulus (G") as well as a higher apparent viscosity. Moreover, the RP/CS complex stabilized emulsions showed a smaller average particle size of 100–1500 nm, a higher zeta-potential of 58–66 mV and better physical stability, thus better tolerating environmental factors such as time, temperature and salt ions. Furthermore, the RP/CS complex stabilized emulsions showed better antioxidant properties with a lower peroxide value (POV) and thiobarbituric acid reactant value (TBARS). Finally, the RP/CS complex emulsions exhibited better antidigestive stability and could slow down the β-carotene release rate. These results provide a theoretical basis for the application of RP/CS complex as a new food emulsifier in the nanocolloid transport system. [Display omitted] • Adding chitosan (CS) made rapeseed protein (RP) more uniform and stable in water. • CS addition improved RP interfacial tension and increased its emulsifying property. • RP/CS complex prevented emulsion stratification and improved its physical stability. • RP/CS complex reduced oil droplets oxidation rate during accelerated oxidation. • RP/CS complex could slow down β-carotene release rate as a stabilizer. [ABSTRACT FROM AUTHOR]

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the effect of silicification on low temperature oxidation characteristics of coal, scanning electron microscopy(SEM) was used to observe the difference of pore structure between silicified coal and non-silicified coal; the temperature programmed test system of spontaneous combustion of coal was used to test the characteristics of low temperature oxidation of two coal samples at different temperatures and the variation rule of indicator gas. On this basis, the oxygen consumption rate at different temperatures in the process of low temperature oxidation was analyzed. The results show that silicification enlarges the pores and increases the specific surface area of coal, on the one hand, it is beneficial to the occurrence of gas in coal, on the other hand, the composite reaction between coal and oxygen is more sufficient, and the silicified coal is easier to oxidize and spontaneous combustion; the volume fraction of the marker gas generated in the oxidation process of silicified coal is always higher than that of non-silicified coal, and when the temperature rises to 110 ℃, the difference in the volume fraction of the gas products of the two coal samples gradually becomes larger, which may be because silicification causes physical and chemical changes in coal body and its molecular structure, leading to oxidation cracking of silicified coal more easily; the rate of oxygen consumption and CO formation of silicified coal is always higher than that of non-silicified coal, indicating that silicification enhances the low temperature oxidation characteristics of coal.

Due to the limitations of utilizing pure metals, several elements were combined to make an alloy in order to provide and improve certain features as needed for the application. The concept of alloy making has diversified over a thousand years. In addition, A new concept of alloy design has been discovered early decades and named high entropy alloy (HEA). Multiple principal elements are being adopted with a high concentration to develop new material. The multi-dimension composition space has several unrevealed properties that the researchers are exposing. However, an ample number of properties have been uncovered. Despite this, alloys based on intermetallic compounds have developed as high-temperature materials with the primary goal of replacing nickel-based superalloys due to their low melting temperatures. For applications in sensitive environments, there is still a lot of interest, thus these alloys are continuously being developed. Mechanical strength, microstructural stability, and corrosion/oxidation resistance are all requirements for alloys used in high-temperature applications. High entropy alloys may be the primary materials used in aviation turbine engine hot section components and high-temperature environments.Nevertheless, there must be many other concealed properties to date, and it is likely to be discovered soon, seeing the ample research going on it. In this urge, this review explores the up-to-the-minute milestones in the high-temperature application achieved by the HEAs. The conversant assessment also includes different processing routes of HEAs, properties at high temperatures, and advanced HEAs that could be exploited for high-temperature applications. In a nutshell, this artifact emphasizes the potential application of HEAs that could be advanced high-temperature materials in the future. Thus, the review outlines HEAs and covers various advantageous information for working on materials exposed to high-temperature applications.

FeAl-based composites with 0, 0.2, 0.5, 0.8 and 1.1 wt.% CNTs were prepared by high-energy ball milling and hot-pressing sintering. The microstructure, mechanical properties and oxidation resistance of CNTs/FeAl composites were tested and analyzed. The results show that the main phases of CNTs/FeAl bulk composites are FeAl phase with B2 structure, α-Al2O3 and AlFe3C0.5. The microstructure distribution is relatively uniform. With the increase of CNTs content, the hardness and tensile strength of CNTs/FeAl composites first increase and then decrease. When the CNTs content is 0.8 wt.%, the two parameters reach the maximum, 53.2% and 25.8% higher than FeAl, respectively. After adding CNTs, the oxidation resistance of CNTs/FeAl composites is improved, and the oxidation weight gain of CNTs/FeAl composites is one order of magnitude lower than that of FeAl alloy. This is due to the presence of thin and dense oxidation film mainly composed of α-Al2O3 and α-Fe2O3 on the material surface. [ABSTRACT FROM AUTHOR]

The object of current research is the oxidation and melting properties of milk fat samples in different heating rates. One of the most problematic issues is the evaluation dependence of temperature and oxidation time regarding to heat flow, and the estimation of attitude of enthalpy values to heating rates. In order to gain a comprehensive assessment of oxidation and melting properties of milk fat samples on differential scanning calorimeter in various heating rates, it is necessary to conduct experimental studies. The analysis was performed using the dynamic option of the differential scanning calorimetry (DSC) with the following sample heating rates: 2.5, 4, 5, 7.5, 10, 12.5, 15 °C⋅min–1. Analyses were performed on 14 samples of milk fat, thus, for each heating rate were intended to two milk fat samples. As a result of the analysis, in the proper heating rates increased, it was found, that the oxidation properties of milk fat depend on the heating rates on DSC examination. In the thermal DSC analysis, the start temperature (Ts) (inlet), the onset temperature (Ton), and the maximum heat flow-peak temperatures (Tp) of oxidation were rising gradually. All the value of oxidation increased gradually with increasing heating rate, only in the Tend values were chainable among all heating rates. However, the oxidation time of milk fat is inversely proportional to the various heating rates in DSC. The oxidation enthalpy was calculated according to the heating rates too. The masses of the samples differ from each other, albeit slightly, which the individuality in the value of enthalpy could be explained through this ratio and duration of exothermic. The melting point considers the important indicator to explain the purity of samples. Melting curves of extracted milk fat samples on DSC were characterized by endothermic behavior and observed with the mild peaks, the first and the second distinct peaks due to the low-melting triacylglycerols (with high unsaturated fatty acids content) and high-melting fats, which present in milk fat. In concluded results, the characteristics of DSC oxidation curves are melting point due to the chemical structure of the fatty acids which milk fat samples contain. [ABSTRACT FROM AUTHOR]

Nickel-based superalloys are in great demand for harsh-service conditions involving high temperatures and oxidative environments. Haynes 282 stands out due to its excellent high-temperature properties and easy fabricability. However, the upper operation temperature of Haynes 282 is limited due to its relatively low liquidus temperature. Equipped with high-fidelity density-functional theory calculations and high-throughput experimentation methodology, we explored new compositional spaces that exhibit higher liquidus temperature and higher strength. While maintaining the manufacturability, the newly designed alloy shows improved strength and ductility at room temperature and better oxidation resistance up to 800 °C. The new compositions showcase a minor change in the refractory and metalloid content can significantly impact the mechanical and oxidation performance of superalloys. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, CrNbTaVW RHEA was produced via vacuum arc melting. The microstructure, hardness, corrosion and oxidation properties were explored in comparison with the commercial IN718 alloy. The results indicated that CrNbTaVW RHEA exhibited a dendritic microstructure that was segregated into BCC1, BCC2, and Cr(VNb) 2 Laves. The CrNbTaVW RHEA has a higher hardness of 688 HV than the IN718 alloy with 301 HV. The higher hardness is due to Laves phase solid solution strengthening and grain refinement. From the corrosion results, CrNbTaVW RHEA had a lower corrosion rate in 3.5 wt% NaCl (0.000097 mm/yr) and 1 M H 2 SO 4 (0.00013 mm/yr) than the commercial IN718 alloy (0.054 mm/yr and 1.12 mm/yr). The cyclic oxidation analysis at 850 °C and 1050 °C after 15 hours confirmed a mass gain of 4.41 mg/cm2 and 10.84 mg/cm2 for IN718 alloy, while CrNbTaVW RHEA exhibited a mass loss of −25.17 mg/cm2 and − 35.91 mg/cm2, respectively, indicating that the IN718 alloy exhibited the best oxidation resistance. Thermal and growth stresses contributed to the pores, voids, cracks, and spallation observed in the CrNbTaVW RHEA. • CrNbTaVW RHEA is segregated into three phases: BCC1, BCC2, and Cr(VNb) 2 Laves. • CrNbTaVW RHEA exhibited a higher hardness than the IN718 alloy. • CrNbTaVW has a lower corrosion rate than IN718 in chloride and acidic solutions. • The IN718 alloy has superior oxidation resistance than the CrNbTaVW RHEA. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to effectively reduce the number of diesel exhaust particles and reduce particulate emissions, it is necessary to have a deep understanding of the mechanical and oxidation characteristics of diesel exhaust particles. For the combustion particles of methanol/biodiesel (BM5, BM10, and BM15), atomic force microscopy and thermogravimetric analyzers were used to study changes of particle in mechanical parameters and oxidation rules, and association impact analysis was performed. Biodiesel (B100) was used as a reference. The results showed that with the increase of methanol content, the attraction force Fat, the cohesive force Fad, the adhesion energy Wad, and Young's modulus E of the methanol/biodiesel particles all decreased significantly. During the oxidation process, the weight loss rate of SOF increased, while the content of soot decreased. In addition, the initial combustion temperature of the SOF component TSOF and soot component Tsoot in particles as well as the burn-out temperature Tend showed a downward trend. There was a certain correlation between the mechanical parameters and the oxidation properties of the particles. The smaller the mechanical parameters, such as the attraction force Fat, viscous force Fad, the cohesive force Fad, the adhesion energy Wad, and Young's modulus E, the greater the looseness of the particles, the smaller the particle hardness and the degree of graphitization. [ABSTRACT FROM AUTHOR]

In this paper, the Aluminum−boron−europium ternary alloy fuels with boron content of 1.5∼4.85 wt. % and europium content of 3 wt. % were prepared by the close‐coupled gas atomization. XRD, SEM, TG‐DTA and oxygen bomb test were used to analyze the phase constituents, morphology, thermal oxidation behavior and combustion exothermic property of powders, respectively. The functions of boron and europium on the combustion of metal fuels were studied, and a reasonable oxidation model of the alloy particles was proposed. The results show that there are Al, AlB2, Al4Eu and B6Eu in the alloy. When the europium content is constant, the combustion enthalpy of the Al−B−Eu alloy powder firstly increases and then decreases as the boron content increases. Additionally, at oxygen pressure of 3.0 MPa, the Al−3.5B−3Eu ternary alloy powder burned completely with the maximum combustion enthalpy of 33324.5 J g−1. This increases by 11 % compared with theoretical combustion enthalpy of aluminum powder (31.1 kJ g−1). Al−3.5B−3Eu undergoes a dramatic oxidation exothermal phenomenon at 1110 °C with the weight increase efficiency of 53.66 %, which is 1.7 times that of aluminum. Due to the synergistic effects between the phase of B6Eu and AlB2 inside the alloy particles, the Al−3.5B−3Eu alloy powder shows excellent exothermic performance. [ABSTRACT FROM AUTHOR]

Abstract Alumina-reinforced copper matrix composites with Ag addition were fabricated by internal oxidation. The effects of slight Ag addition (0.92 at%) on electrical conductivity (EC) and oxidation resistance of internal-oxidized copper alumina composites were investigated. The annealing treatments were carried out to promote the diffusion of Ag in copper matrix. Ag was observed to segregate at Cu/Al 2 O 3 interface after being annealed, which may lead to the lower interfacial energy between Al 2 O 3 and copper matrix. The EC increased more than 7.8% after Ag was added. Moreover, annealing Cu Al 2 O 3 Ag composite at 500 °C for 10 h results in the improvements of both oxidation resistance and EC. The initial oxidation temperature increased from 169 °C to 189 °C and the EC increased from 81.98 ± 0.56% International Annealed Copper Standard (IACS) to 88.19 ± 0.27%IACS. While the EC of Cu Al 2 O 3 composites always remained ∼76%IACS which suggests that the annealing treatment has insignificant impacts on EC of Cu Al 2 O 3 without Ag. Highlights • Copper-alumina composites were fabricated by internal oxidation. • Annealing treatments can influence the position of Ag atoms in copper matrix. • Ag was found to segregate and precipitate at Cu/Al2O3 interface. • Both desired oxidation and electrical properties were achieved. [ABSTRACT FROM AUTHOR]

This paper explores the effects of adding rare earth elements (lanthanum or erbium) on the oxidation properties of Ti-43.5Al-4Nb-1Mo-0.1B (TNM) alloy. Isothermal oxidation tests were performed under air atmosphere at 900 and 1000 °C. Mass gain was measured in several steps during the oxidation test, and the oxidized specimens were characterized by XRD and FE-SEM. The results showed that while adding 0.1 at.% rare earth elements (REEs) reduced oxidation rate of the TNM alloy, 0.2 at.% REEs addition increased the mass gain of the alloys. The oxidation curves were fitted by a power-law equation; the results showed that the oxidation kinetic curves of all alloys obeyed parabolic growth kinetics (n = 2). Meanwhile, the activation energy of oxidation was in the range of 40-50 kCal/mol, thereby suggesting that the scale growth was controlled by mass transport in the TiO2 layer. Also, the results of the scale characterization showed that addition of REEs at low level (e.g., 0.1 at.%) could reduce diffusion rate in the scale. However, addition of the higher amounts of La or Er (e.g., 0.2 at.%) due to the lower valency (+ 3) of these elements, as compared with Ti (+ 4), could lead to the increased anion diffusion, the formation of hillocks in the scale and a rise of the oxidation rate. [ABSTRACT FROM AUTHOR]

Chia ( Salvia hispanica L.) seed oil is the richest natural source of α-linolenic acid, an n − 3 polyunsaturated fatty acid (ω-3 PUFA), contributing to its use as functional and nutraceutical food in large part of Latin America. However, a food with such fatty acid composition could be highly susceptible to lipid oxidation. Thus, the present study was conducted to determine the thermal and oxidative stability of chia oil by various methods. Rancimat method was used to evaluate the effect of synthetic and natural antioxidants in the oxidative stability. Pressurized differential scanning calorimetry (PDSC), Schaal test and H NMR spectroscopy were used to assess the thermal stability. The effect of frying temperature and/or heating time on fatty acid composition was assessed by H NMR. The results show that tert-butylhydroquinone (TBHQ) and a mixture of TBHQ and rosemary extract were effective in increasing the oxidative stability of chia oil. Concerning the storage conditions, PDSC, Schaal test and H NMR data showed that chia oil is stable at 60 °C; hence, there is no need for special storage conditions. PDSC and H NMR results indicate that chia oil cannot be used in cooking and frying, because at high temperatures severe degradation of the unsaturated groups and loss of the nutritional properties of the oil occur. [ABSTRACT FROM AUTHOR]

• The changes of OC/EC, PAHs and water-soluble ions in particulate matter were analyzed by means of elemental carbon/organic carbon analyzer. • The oxidation characteristics of the particulate matter were obtained using a thermogravimetric analyser and correlated with changes in the chemical composition of the particulate matter. • As the methanol blending ratio increases, the mass concentrations of OC, bicyclic and tricyclic PAHs in the particulate matter increase, the mass concentrations of EC decrease. • As the methanol blending ratio increases, the activation energy of the particles decreases and the oxidation activity increases, and there is a correlation between the oxidation properties of the particles and the chemical components. When diesel engines burn different fuels, the chemical composition of the emitted combustion particles changes, leading to changes in the oxidation characteristics of these particles and determining the regeneration strategy and service life of after treatment devices. In order to investigate the influence of methanol/biodiesel fuel mixtures on the chemical composition and oxidation activity of emitted soot matter, a test bench was built using a four-cylinder diesel engine, and soot matter in the exhaust was collected. Tests used mixed fuel with different methanol mixing ratios. By using a high-performance liquid chromatograph, a thermogravimetric analyzer, and other equipment, the changes of chemical composition and oxidation characteristics of particles were studied. The results show that as the methanol mixing ratio increases, the mass concentration of organic carbon (OC), bicyclic, and tricyclic polycyclic aromatic hydrocarbons (PAHs) in the particles increase, the mass concentration of elemental carbon (EC) and high molecular weight PAHs decreases, the concentration of nitrate ions first increases and then decreases, the activation energy decreases, and the oxidation activity increases. In general, the chemical composition of combustion particulates from methanol/biodiesel changes, and the oxidation activity is greatly improved. This research work can provide a reference for the coating design and regeneration strategy for optimizing diesel particulate filters (DPFs). [ABSTRACT FROM AUTHOR]

The anatase TiO 2 single crystals were synthesized through a solvothermal route and their morphology and structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Energy Dispersive X-ray Spectrometer (EDX). Characterization and photocatalytic activity experiments proposed that the simultaneous exposure of (001) and (101) facets could facilitate charge separation. While, due to the effect of surface substitution, the (001) facets were easier to be corroded with the increasing synthesis time. Moreover, the as-synthesized anatase TiO 2 single crystals with (001) facets showed superior photocatalytic oxidation properties. Besides, the research on the plausible competitive mechanism of oxidation and reduction in the same reaction system suggested that the oxidation reaction was the predominant one with the increasing proportion of water on anatase TiO 2 single crystals possessing the high reactivity of the (001) facets. [ABSTRACT FROM AUTHOR]

[Display omitted] • A newly developed variable pressure laminar flow reactor was used for experiments. • Speciation profiles of two propanol isomers were obtained at elevated pressure. • Modified kinetic model of two propanol isomers for oxidation was developed. • Effects of molecular structure of propanol isomers on oxidation have been analyzed. Fuel combustion mechanism at different temperature and pressure range can be highly divers. In combustion process, many reactions are strongly pressure-dependent. Reactions that are important at low pressures may not be that important when pressure gets higher. Kinetic models developed and validated only at atmospheric conditions can have a large deviation when directly applied for higher pressures. Thus, experimental and kinetic studies at elevated to high pressures are essential for the understanding of fuel properties at engine-relevant conditions. However, speciation studies at such conditions are rare, which limits prediction accuracy of kinetic models. Propanol is the smallest alcohol that has isomers, and can be produced via carbon–neutral routes. Study on propanol can reveal the effect of isomerization and facilitate kinetic studies of larger alcohols. In present work, experiments have been carried out at elevated pressure in a variable pressure laminar flow reactor. Speciation data has been measured and compared. Moreover, a previous kinetic model has been modified and validated to improve prediction accuracy at elevated pressure and has been used for further kinetic analysis. The structural difference between two isomers affects their oxidation pathways and intermediate species. The position of hydroxyl moiety and bond dissociation energy of α -H have led to different oxidation properties of these two isomers. Through present work, the effect of molecular structure on oxidation properties of propanol isomers at elevated pressure have been studied. Speciation database of propanol isomers at elevated pressure has been enriched, and prediction accuracy of a previous model at present conditions has been improved. [ABSTRACT FROM AUTHOR]

A protective MoSi coating on Nb substrate was prepared by air plasma spraying and annealing followed by siliconizing. The influence of annealing for plasma-sprayed Mo layer on the subsequent preparation of MoSi coating was investigated. Oxidation behavior of the MoSi coating was investigated at 1200 °C in air. Phase constituents and microstructure of the MoSi coating were characterized by x-ray diffraction and scanning electron microscopy. High-temperature annealing significantly decreases the porosity of the as-sprayed Mo coating (from 9.6 to 2.1%). After vacuum annealing, the splat boundaries and lamellar microstructure of the as-sprayed coating disappear and the recrystallized structure of the Mo coating appears. The MoSi coating falls off from the surface of the as-sprayed Mo coating during siliconizing process. The MoSi coating prepared on the annealed Mo layer surface has a dense microstructure, which shows a good interface bond between the coating and the Nb substrate. The coating has a multilayer structure, with MoSi outer layer, Mo middle layer, and Mo-Nb alloy inner layer. The MoSi coating exhibits an excellent oxidation resistance at 1200 °C in air. [ABSTRACT FROM AUTHOR]

The content and the existing form of refractory elements significantly affect the performance in service of superalloys, which has gained extensive attention in this field. In this study, basic influence rule of diverse Ta and Ti contents on the microstructure and properties of the novel γ′ phase strengthened Co–Ni-based superalloys is clarified by thermodynamic calculation and experimental research. Under the premise of a total Ta and Ti content of 5 at%, increasing Ta content elevates the solvus temperature of γ′ phase and volume fraction of Laves phase, and also reduces the volume fraction of β phase in the as-cast alloys. Moreover, the average size of γ′ phase goes down and the coarsening of γ′ phase is inhibited simultaneously in the alloy after aging treatment. Consequently, increasing the content of Ta can enhance the microstructure stability and elevates the Vickers hardness and yield strength of the alloy. However, the density and cost of the alloy have to be raised. Meanwhile, the variation of Ta and Ti contents affects the oxidation performance of the alloys by influence the volatilization of W and Mo oxides. 2Ta3Ti and 3Ta2Ti alloys possess favorable oxidation resistance at 1050 °C. Considering the effect of Ta and Ti elements and normal performance requirements of Ni-based superalloys, 3Ta2Ti alloy has more impressive engineering application prospects. This work provides a solid foundation for optimizing the composition and improving the properties of Co–Ni-based superalloys. • Influence law of Ta and Ti content on the microstructure & properties of the alloy was clarified. • Increasing Ta content raises the mechanical properties, density and cost. • The variation of Ta and Ti contents affects the oxidation behavior of the alloys. • The 3Ta2Ti alloy has more impressive engineering application prospects. [ABSTRACT FROM AUTHOR]

In order to protect Niobium material from oxidation, MoSi 2 coating was prepared on the Niobium substrate by spark plasma sintering. Oxidation behavior of MoSi 2 coating was investigated in air over the temperature range of 1200–1500 °C. The interfacial diffusion between MoSi 2 coating and Niobium substrate was also examined. Dense MoSi 2 coating was successfully prepared using spark plasma sintering. The porosities of top and side coatings are about 5.5% and 6.4%, respectively. No cracks were present in the MoSi 2 coating. Cracking and spallation of the SiO 2 scale did not occur at test temperatures. Two intermediate phases—(Nb,Mo) 5 Si 3 and Nb 5 Si 3 phases, were detected in the boundary of MoSi 2 coating and Nb substrate. The growth of the reaction layer was dominated by the diffusion of Si toward the Nb substrate and obeyed a parabolic rate law. A multi-layered structural coating formed on Nb substrate, which consisted of MoSi 2 , (Mo,Nb) 5 Si 3 and Nb 5 Si 3 in turn. [ABSTRACT FROM AUTHOR]

Abstract: The structure and oxidation properties of cooked cured meat pigment (CCMP) were investigated by comparing the change in spectra of CCMP before and after oxidisation. CCMP was extracted using petroleum ether/acetone/ethyl acetate step by step from precooked cured beef. The extracted sample was oxidised by being exposed to air with normal lighting or adding 1.5ppm H2O2, respectively. The structure of CCMP was identified as a pentacoordinate mononitrosylheme complex by electron paramagnetic resonance (EPR), HPLC/ESI-HR-MS, Raman and FT–IR spectra. The changed EPR spectra of CCMP in acetone oxidised under different conditions suggested a new proposal that the NO− group might not detach itself from iron porphyrin during oxidation in air with normal lighting, but changed in conjugated structure, and the structure tended to axial symmetry by analysis of the changes in g factor. This hypothesis was further supported by the results of the HPLC/ESI-HR-MS and Raman spectrum. [Copyright &y& Elsevier]

Abstract: Oxidation properties of niobium and tin in mesoporous matrices were investigated in oxidation of cyclic ketones, cyclic olefins and cyclic keto-olefins with hydrogen peroxide as an oxidation agent. Mesoporous molecular sieves of MCM-41 and MCM-48 types were synthesized and niobium and tin were incorporated into the structure. X-ray diffraction and nitrogen sorption isotherms confirmed a high-quality of these mesoporous molecular sieves even after incorporation of Nb and/or Sn. It was shown that niobium selectively oxidizes double bond of the substrates to epoxide followed by further hydration and forms diols and keto-diols in the second step of the reaction. On the other hand, tin carries out Baeyer–Villiger oxidation of cyclic ketones to lactones without further consecutive reactions while Nb is inactive in this reaction. When substrate contains both Cbond and carbonyl group on the same ring, Nb oxidizes preferentially the double bond with a much higher activity than Sn. [Copyright &y& Elsevier]

Abstract: In this paper, SiC coating on three-dimensional (3-D) braided carbon fiber was obtained, which was infiltrated with SiO2 sol into 3-D braided carbon fiber and then carbon–thermal reduced. The effect of carbon–thermal reduction process was examined. Thermal–oxidative stability of the 3-D braided carbon fiber coated with SiC was compared with original 3-D braided carbon fiber. The oxidation stability of the SiC coating/3-D braided carbon fiber was extended up to 900–1000 °C. After exposure to air at 900–1000 °C , the residual weight of the composite was 26–30%. [Copyright &y& Elsevier]

The XRD, SEM, isothermal oxidation-weight loss and non-isothermal thermogravimetry (TG)–differential thermogravimetry (DTG) were used to study the oxidation properties and oxidation decomposition kinetics of three-dimensional (3-D) braided carbon fiber (abbreviated as fiber). The results showed that the non-isothermal oxidation process of fiber exhibited self-catalytic characteristic. The kinetic parameters and oxidation mechanism of fiber were studied through analyzing the TG and DTG data by differential and integral methods. The oxidation mechanism was random nucleation, the kinetic parameters were: lg A=10.299 min−1; Ea=156.29 kJ mol−1. [Copyright &y& Elsevier]

Abstract: Diamond film is an ultra-durable optical material with high thermal conductivity and good transmission in near-infrared and far-IR (8–14μm) wavebands. CVD diamond is subjected to oxidation at temperature higher than 780°C bared in air for 3min, while it can be protected from oxidation for extended exposure in air at temperature up to 900°C by a coating of aluminum nitride. Highly oriented AlN coatings were prepared for infrared windows on diamond films by reactive sputtering method and the average surface roughness (R a) of the coatings was about 10nm. The deposited films were characterized by X-ray diffraction (XRD) and atom force microscope (AFM). XRD confirmed the preferential orientation nature and AFM showed nanostructures. Optical properties of diamond films coated AlN thin film was investigated using infrared spectrum (IR) compared with that for as-grown diamond films. [Copyright &y& Elsevier]