Enhanced high-temperature performance of Li-rich layered oxide via surface heterophase coating

Li-rich layered oxides have become one of the most concerned cathode materials for high-energy lithiumion batteries, but they still suffer from poor cycling stability and detrimental voltage decay, especially at elevated temperature. Herein, we proposed a surface heterophase coating engineering based on amorphous/crystalline Li3 PO4 to address these issues for Li-rich layered oxides via a facile wet chemical method. The heterophase coating layer combines the advantages of physical barrier effect achieved by amorphous Li3 PO4 with facilitated Li+diffusion stemmed from crystalline Li3 PO4. Consequently, the modified Li(1.2) Ni(0.2) Mn(0.6) O2 delivers higher initial coulombic efficiency of 92% with enhanced cycling stability at 55 °C(192.9 mAh/g after 100 cycles at 1 C). More importantly, the intrinsic voltage decay has been inhibited as well, i.e. the average potential drop per cycle decreases from 5.96 mV to 2.99 mV. This surface heterophase coating engineering provides an effective strategy to enhance the high-temperature electrochemical performances of Li-rich layered oxides and guides the direction of surface modification strategies for cathode materials in the future.

Corrosion evolution of high-temperature formed oxide film on pure Sn solder substrate

The evolution of morphology, composition, thickness and corrosion resistance of the oxide film on pure Sn solder substrate submitted to high-temperature aging in 150 °C dry atmosphere was investigated. The results indicate that high-temperature aging accelerates the dehydration of Sn(OH)_(4)in the pre-existing native oxide film to form SnO_(2)and facilitates the oxidation of fresh Sn substrate, resulting in the gradual increase in oxide film thickness and surface roughness with prolonging aging time. However, the corrosion resistance of the film initially is enhanced and then deteriorated with an extending aging time. Besides, the formation and evolution mechanisms of the oxide film with aging time were discussed.

High-temperature stress suppresses allene oxide cyclase 2 and causes male sterility in cotton by disrupting jasmonic acid signaling

Cotton(Gossypium spp.) yield is reduced by stress. In this study, high temperature(HT) suppressed the expression of the jasmonic acid(JA) biosynthesis gene allene oxide cyclase 2(GhAOC2), reducing JA content and causing male sterility in the cotton HT-sensitive line H05. Anther sterility was reversed by exogenous application of methyl jasmonate(MeJA) to early buds. To elucidate the role of GhAOC2 in JA biosynthesis and identify its putative contribution to the anther response to HT, we created gene knockout cotton plants using the CRISPR/Cas9 system. Ghaoc2 mutant lines showed male-sterile flowers with reduced JA content in the anthers at the tetrad stage(TS), tapetum degradation stage(TDS), and anther dehiscence stage(ADS). Exogenous application of MeJA to early mutant buds(containing TS or TDS anthers) rescued the sterile pollen and indehiscent anther phenotypes, while ROS signals were reduced in ADS anthers. We propose that HT downregulates the expression of GhAOC2 in anthers, reducing JA biosynthesis and causing excessive ROS accumulation in anthers, leading to male sterility. These findings suggest exogenous JA application as a strategy for increasing male fertility in cotton under HT.

Synthesis of phosphonated graphene oxide by electrochemical exfoliation to enhance the performance and durability of high-temperature proton exchange membrane fuel cells

The doping of functionalized graphene oxide(GO)in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells(HT-PEMFC).Phosphonated graphene oxide(PGO)with a P/O ratio of 8.5%was quickly synthesised by one-step electrochemical exfoliation based on a three-dimensiaonal(3D)printed reactor and natural graphite flakes.Compared with the GO prepared by the two-step electrochemical exfoliation method,the PGO synthesized by the one-step electrochemical exfoliation can better improve the performance of the membrane-electrode-assembly(MEA)based on the polybenzimidazole(PBI)membrane in the HTPEMFC.The doping of 1.5 wt%GO synthesised by electrochemical exfoliation with the 2-step method or reactor method in PBI increased the peak power density by 17.4%or 35.4%compared to MEA based on pure PBI membrane at 150℃,respectively.In addition,the doping of PGO in PBI improves its durability under accelerated stress test(AST).

Effect of La_2O_3/Ce O_2 particle size on high-temperature oxidation resistance of electrodeposited Ni-La_2O_3/Ce O_2 composites

Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.

Influencing factors and mechanism of high-temperature oxidation of high-entropy alloys: A review

High-temperature oxidation is a common failure in high-temperature environments,which widely occur in aircraft engines and aerospace thrusters;as a result,the development of anti-high-temperature oxidation materials has been pursued.Ni-based alloys are a common high-temperature material;however,they are too expensive.High-entropy alloys are alternatives for the anti-oxidation property at high temperatures because of their special structure and properties.The recent achievements of high-temperature oxidation are reviewed in this paper.The high-temperature oxidation environment,temperature,phase structure,alloy elements,and preparation methods of high-entropy alloys are summarized.The reason why high-entropy alloys have anti-oxidation ability at high temperatures is illuminated.Current research,material selection,and application prospects of high-temperature oxidation are introduced.

Micro-analysis of high-temperature oxidation-resistance of a new kind of heat-resistant grid plate in grate-kiln

To further improve the oxidation-resistance of materials and reduce the cost of grid plates in grate-kiln, a new kind of heat-resistant grid plate was developed. The microstructure of this grid plate with a life more than 18 months was studied by XRD, SEM and EDS techniques. The results show that high hardness, high intensity and good impact property make the new kind of heat-resistant grid plate and its oxide film have a higher resistance to deformation and abrasion at 900-1000℃ Besides, small grain size is beneficial to form a complete protective oxide film. The oxide film composed of SiO2 layer, Cr2O3 layer and Fe2O3 layer is rather thin and bonds closely with the backing. The forming of the chemical stable nickel-rich layer increases the density of Cr2O3 layer.

Diet with high content of advanced glycation end products induces oxidative stress damage and systemic inflammation in experimental mice: protective effect of peanut skin procyanidins

Non-enzymatic glycation reaction in food can produce diet-derived advanced glycation end products(dAGEs),which have potential health risks.Thus,it is of great significance to find efficient substances to improve the negative effects induced by dAGEs on human health.This study investigated the intervening effects of peanut skin procyanidins(PSP)on the dAGEs-induced oxidative stress and systemic inflammation in experimental mice model.Results showed that the accumulation of AGEs in serum,liver,and kidney was significantly increased after mice were fed dAGEs(P<0.05).The expression of advanced glycation product receptor(RAGE)was also significantly increased in liver and kidney(P<0.05).PSP could not only effectively reduce the accumulation of AGEs in serum,liver and kidney of mice,but also reduce the expression of RAGE in liver and kidney of mice.And the levels of pro-inflammatory cytokines interleukin-6(IL-6),tumor necrosis factor(TNF-α),and IL-1βin serum of mice were significantly decreased(P<0.05),while the levels of antiinflammatory factor IL-10 were increased,and the inflammatory injury in mice was improved.In addition,the levels of superoxide dismutase(SOD),glutathione(GSH),catalase(CAT)in liver and kidney of mice were increased(P<0.05),and the level of malondialdehyde(MDA)was decreased(P<0.05),which enhanced the antioxidant capacity of mice in vivo,and improved the oxidative damage of liver and kidney.Molecular docking technique was used to confirm that the parent compound of procyanidins and its main metabolites,such as 3-hydroxyphenylacetic acid,could interact with RAGE,which might inhibit the activation of nuclear transcription factor(NF-κB),and ultimately reduce oxidative stress and inflammation in mice.

Effect of inner oxidant on self-propagating high-temperature synthesis of MnZn-ferrite powder

Using KClO3 as an inner oxidant, MnZn-ferrite powder was synthesized by a self-propagating high-temperature synthesis (SHS) process in normal air atmosphere. The effects of the inner oxidant on combustion temperature, combustion velocity, microstructure and the phase of the product were investigated by XRD and SEM,respectively. The results show that a highly ferritized powder can be obtained as well as the highest combustion temperature and the highest combustion velocity when the inner oxidant content m equals 54(k-16).

High-temperature oxidation behavior of 9Cr‒5Si‒3Al ferritic heat-resistant steel

To improve the oxidation properties of ferritic heat-resistant steels,an Al-bearing 9Cr‒5Si‒3Al ferritic heat-resistant steel was designed.We then conducted cyclic oxidation tests to investigate the high-temperature oxidation behavior of 9Cr‒5Si and 9Cr‒5Si‒3Al ferritic heat-resistant steels at 900 and 1000℃.The characteristics of the oxide layer were analyzed by X-ray diffraction,scanning electron microscopy,and energy dispersive spectroscopy.The results show that the oxidation kinetics curves of the two tested steels follow the parabolic law,with the parabolic rate constant kp of 9Cr‒5Si‒3Al steel being much lower than that of 9Cr‒5Si steel at both 900 and 1000℃.The oxide film on the surface of the 9Cr‒5Si alloy exhibits Cr2MnO4 and Cr2O3 phases in the outer layer after oxidation at 900 and 1000℃.However,at oxidation temperatures of 900 and 1000℃,the oxide film of the 9Cr‒5Si‒3Al alloy consists only of Al2O3 and its oxide layer is thinner than that of the 9Cr‒5Si alloy.These results indicate that the addition of Al to the 9Cr‒5Si steel can improve its high-temperature oxidation resistance,which can be attributed to the formation of a continuous and compact Al2O3 film on the surface of the steel.

Analysis on high-temperature oxidation and growth stress of iron-based alloy using phase field method

High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is a complex process involving microstructure evolution, its quantitative analysis has always been a challenge. In this work, a phase field method （PFM） based on the thermodynamics theory is developed to simulate the oxidation behavior and oxidation induced growth stress. It involves microstructure evolution and solves the problem of quantitatively computational analysis for the oxidation behavior and growth stress. Employing this method, the diffusion process, oxidation performance, and stress evolution axe predicted for Fe-Cr-A1-Y alloys. The numerical results agree well with the experimental data. The linear relationship between the maximum growth stress and the environment oxygen concentration is found. PFM provides a powerful tool to investigate high-temperature oxidation in complex environments.

Comparative investigation of microstructure and high-temperature oxidation resistance of high-velocity oxy-fuel sprayed CoNiCrAlY/nano-Al_(2)O_(3) composite coatings using satellited powders

Satellited CoNiCrAlY–Al_(2)O_(3)feedstocks with 2wt%, 4wt%, and 6wt% oxide nanoparticles and pure CoNiCrAlY powder were deposited by the high-velocity oxy fuel process on an Inconel738 superalloy substrate. The oxidation test was performed at 1050℃ for 5, 50, 100,150, 200, and 400 h. The microstructure and phase composition of powders and coatings were characterized by scanning electron microscopy and X-ray diffraction, respectively. The bonding strength of the coatings was also evaluated. The results proved that with the increase in the percentage of nanoparticles(from 2wt% to 6wt%), the amount of porosity(from 1vol% to 4.7vol%), unmelted particles, and roughness of the coatings(from 4.8 to 8.8 μm) increased, and the bonding strength decreased from 71 to 48 MPa. The thicknesses of the thermally grown oxide layer of pure and composite coatings(2wt%, 4wt%, and 6wt%) after 400 h oxidation were measured as 6.5, 5.5, 7.6, and 8.1 μm, respectively.The CoNiCrAlY–2wt% Al_(2)O_(3)coating showed the highest oxidation resistance due to the diffusion barrier effect of well-dispersed nanoparticles. The CoNiCrAlY–6wt% Al_(2)O_(3)coating had the lowest oxidation resistance due to its rough surface morphology and porous microstructure.

High-temperature oxidation behavior of heat resistant stainless steel 1.4828

The kinetic curves of the high-temperature oxidation of austenitic heat resistant stainless steel 1. 4828 at 1 050 ℃ were measured using a weighing method. It is shown that the oxidation curves at 1 050 ℃ followed the parabolic line law, and after 250 h of oxidation, the mass gain was about 80 g/m2. The surface morphology and structure of the oxide layers were studied by scanning electron microscopy and X-ray diffraction. A complicated oxide layer obtained at 1 050 ℃ was mainly composed, from inner to outer, of （FeSi） 3 04, Cr2 03, Fe2 03, and spinel oxides FeCr204 and NiMn204.

High-temperature oxidation behavior of austenitic stainless steel Cr20Ni12Si2RE

Austenitic stainless steel Cr20 Ni12 Si2 RE was developed for use in hot-end components of automobile exhaust systems,especially in automobiles designed according to the China VI emission standard. The hightemperature oxidation kinetic curve of Cr20 Ni12 Si2 RE at 1 050 ℃ was obtained using the weighting method. The oxidation curves exhibit the parabolic law at 1 050 ℃; after 250 h of oxidation,the mass gain was 22 g/m^2. The morphology,structure,and composition of the oxide film were examined using scanning electron microscopy and Xray diffraction methods. A thin,stable,and dense spinel oxide film obtained after 250 h of oxidation at 1 050 ℃ was mainly composed of( Mn_(0.87)Fe_(0.13))( Mn_(0.13)Fe_(0.87)Cr) O_4 and Cr_2 O_3 with a silicon-containing oxide underneath. The addition of rare earth elements was found to restrict further diffusion of metallic atoms from the austenite toward the oxide film,and consequently,led to a low growth rate of the oxide film. The inner silicon-containing oxide was produced by the diffusion of oxygen atoms and enhanced the coherent strength of the oxide film.

Recent advances in phosphoric acid-based membranes for high-temperature proton exchange membrane fuel cells

High-temperature proton exchange membrane fuel cells(HT-PEMFCs)are pursued worldwide as efficient energy conversion devices.Great efforts have been made in the area of designing and developing phosphoric acid(PA)-based proton exchange membrane(PEM)of HT-PEMFCs.This review focuses on recent advances in the limitations of acid-based PEM(acid leaching,oxidative degradation,and mechanical degradation)and the approaches mitigating the membrane degradation.Preparing multilayer or polymers with continuous network,adding hygroscopic inorganic materials,and introducing PA doping sites or covalent interactions with PA can effectively reduce acid leaching.Membrane oxidative degradation can be alleviated by synthesizing crosslinked or branched polymers,and introducing antioxidative groups or highly oxidative stable materials.Crosslinking to get a compact structure,blending with stable polymers and inorganic materials,preparing polymer with high molecular weight,and fabricating the polymer with PA doping sites away from backbones,are recommended to improve the membrane mechanical strength.Also,by comparing the running hours and decay rate,three current approaches,1.crosslinking via thermally curing or polymeric crosslinker,2.incorporating hygroscopic inorganic materials,3.increasing membrane layers or introducing strong basic groups and electron-withdrawing groups,have been concluded to be promising approaches to improve the durability of HT-PEMFCs.The overall aim of this review is to explore the existing degradation challenges and opportunities to serve as a solid basis for the deployment in the fuel cell market.

Effect of La_2O_3 on microstructure and high-temperature wear property of hot-press sintering FeAl intermetallic compound

FeAl intermetallic compound with different contents of rare earth oxide La2O3 addition was prepared by hot pressing the mechanically alloyed powders.Effect of La2O3 on microstructure and high-temperature wear property of the sintered FeAl samples was investigated in this paper.The results showed that 1 wt.% La2O3 addition could refine the microstructure and increase the density of the FeAl intermetallic compound,and correspondingly improved the high-temperature wear resistance.SEM and EDS analyses of the wo...

Overcoming coke formation in high-temperature CO_(2)electrolysis

High-temperature CO_(2)reduction reaction(HT-CO_(2)RR)in solid oxide electrochemical cells(SOECs)features near-unity selectivity,high energy efficiency,and industrial relevant current density for the production of CO,a widely-utilized“building block”in today’s chemical industry.Thus,it offers an intriguing and promising means to radically change the way of chemical manufacturing and achieve carbon neutrality using renewable energy sources,CO_(2),and water.Albeit with the great potential of HT-CO_(2)RR,this carbon utilization approach,unfortunately,has been suffering coke formation that is seriously detrimental to its energy efficiency and operating lifetime.In recent years,much effort has been added to understanding the mechanism of coke formation,managing reaction conditions to mitigate coke formation,and devising coke-formation-free electrode materials.These investigations have substantially advanced the HT-CO_(2)RR toward a practical industrial technology,but the resulting coke formation prevention strategies compromise activity and energy efficiency.Future research may target exploiting the control over both catalyst design and system design to gain selectivity,energy efficiency,and stability synchronously.Therefore,this perspective overviews the progress of research on coke formation in HT-CO_(2)RR,and elaborates on possible future directions that may accelerate its practical implementation at a large scale.

Effect of Ti and Ta content on the oxidation resistance of Co-Ni-based superalloys

Co-Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue resistance.Therefore,these alloys show potential as crucial high-temperature structural materials for aeroengine and gas turbine hot-end components.Our previous work elucidated the influence of Ti and Ta on the high-temperature mechanical properties of alloys.However,the intricate interaction among elements considerably affects the oxidation resistance of alloys.In this paper,Co-35Ni-10Al-2W-5Cr-2Mo-1Nb-xTi-(5−x)Ta alloys(x=1,2,3,4)with varying Ti and Ta contents were designed and compounded,and their oxidation resistance was investigated at the temperature range from 800 to 1000℃.After oxidation at three test conditions,namely,800℃for 200 h,900℃for 200 h,and 1000℃for 50 h,the main structure of the oxide layer of the alloy consisted of spinel,Cr_(2)O_(3),and Al_(2)O_(3)from outside to inside.Oxides consisting of Ta,W,and Mo formed below the Cr_(2)O_(3)layer.The interaction of Ti and Ta imparted the highest oxidation resistance to 3Ti2Ta alloy.Conversely,an excessive amount of Ti or Ta resulted in an adverse effect on the oxidation resistance of the alloys.This study reports the volatilization of W and Mo oxides during the oxidation process of Co-Ni-based cast superalloys with a high Al content for the first time and explains the formation mechanism of holes in the oxide layer.The results provide a basis for gaining insights into the effects of the interaction of alloying elements on the oxidation resistance of the alloys they form.

High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide

Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature applications.Following the concept of high entropy,high-entropy fluorite oxides(HEFOs)have showcased intriguing high-temperature application potential.However,unlocking this potential necessitates an assessment of their long-term stability under high-temperature conditions.In this study,we conducted a prolonged heat treatment at 1000℃on typical HEFO,specifically(CeHfZrGdLa)O_(x).After 100 h,high-intensity X-ray diffraction(XRD)revealed a transition from a single-phase fluorite to a multi-phase configuration.Further investigation by analytical electron microscoy(AEM)demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures,leading to spontaneous segregation and separation of Ce and La elements,forming Ce-rich,La-poor,and La-rich phases.Notably,the La-rich phase spontaneously transformed from a fluorite structure(space group Fm3m)to a bixbyite structure(space group Ia3)at elevated temperatures,resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction patterns.Despite the intricate phase decomposition,the energy band gap showed minimal variation,suggesting potential property stability of(CeHfZrGdLa)O_(x)across a broad range of compositions.These findings offer valuable insights into the future applications of HEFOs.

Experimental analysis of HR-120 alloy used for high-temperature fans

High-temperature circulating fans blow 800 ℃ HN protective atmosphere to the surface of the strip as a jet heating power source or suspending source,playing a core role in metal strip continuous annealing furnaces. In this study,several high-temperature alloys were experimentally compared based on their high-temperature mechanical properties,high-temperature creep resistance,and high-temperature oxidation resistance. The results indicate that though the price of HR-120 alloy is only half of Inconel 601,it is suitable for the manufacture of fans that can withstand a high temperature of 800 ℃ given its good creep resistance,high-temperature oxidation resistance,and price advantage.