Hot deformation behavior of Super304H austenitic heat resistant steel

The hot compression tests of Super304H austenitic heat resistant steel were carried out at 800-1200℃and 0.005-5 s^-1 using a Gleeble 3500 thermal-mechanical simulator,and its deformation behavior was analyzed.The results show that the flow stress of Super304H steel decreases with the decrease of strain rate and the increase of deformation temperature; the hot deformation activation energy of the steel is 485 kJ/mol.The hot deformation equation and the relationship between the peak stress and the deformation temperature and strain rate is obtained.The softening caused by deformation heating cannot be neglected when both the deformation temperature and strain rate are higher.

Bismuth Oxide Selenium/Graphene Oxide Composites:Toward High-Performance Electrodes for Aqueous Alkaline Battery

Aqueous alkaline battery represents a promising energy storage technology with both high energy density and high power density as rechargeable batteries.However,the low theoretical capacities,kinetics and stability of anode materials have limited their developments and commercializations.In this study,we propose a novel method to produce two-dimensional layered bismuth oxide selenium(Bi_(2)O_(2)Se)and reduced graphene oxide(r GO)composites via a one-step hydrothermal method.The volume change caused by phase change during rapid charging and discharging is significantly reduced and the capacity reaches 263.83 m Ah g^(-1)at a current density of 0.5 A g^(-1).The Bi_(2)O_(2)Se/r GO electrode exhibits excellent cycling stability in which the capacity retention rate is 81.04%after 5000 cycles.More importantly,the Bi_(2)O_(2)Se/r GO nanosheet composite is used as the anode electrode material with MnCo_(2)O_(4.5)@Ni(OH)_(2)as the cathode electrode material in aqueous alkaline battery.When the energy density is 76.16 W h kg^(-1),the power density reaches 308.65 W kg^(-1).At a power density of 10.21 k W kg^(-1),the energy density remains as high as 33.86 W h kg^(-1).The results presented here may advance the understanding of the issues facing the development of aqueous battery anode materials.

Printable,flexible ceramic fiber paper based on electrospinning

Based on the fact that it is challenging for the polymer flexible circuit substrates to meet the requirements of serving in high-temperature environments,this work proposed the idea of using printable ceramic fiber paper as a high-temperature flexible circuit substrate.A ceramic fiber paper with all ceramic components had been developed via electrospinning,solving the problems of low strength and severe strength drop at high temperatures of traditional ceramic fiber paper.The tensile strength of the prepared ceramic fiber paper is 2.63 MPa,and the reliable service temperature is 1200℃.Its bulk density is about 1.5 times that of traditional ceramic fiber paper.It can be printed with patterns by commercial inkjet printers like ordinary printing paper and has excellent printability.The feasibility of ceramic fiber paper as a flexible circuit substrate was verified by constructing a simple circuit.When the fiber paper is significantly bent,the circuit still forms a complete path,which proves that it has a strong application potential for high-temperature flexible circuit substrate and is expected to promote the development of flexible electronic devices serving at extreme high-temperature environments.

High mass-loading and binder-free flexible vanadium-based oxide cathode for zinc-ion battery via a bridge of MXene

Flexible zinc-ion batteries(ZIBs)are promising power sources for portable devices due to their high safety and low production cost.However,the low mass-loading and limited areal capacity of cathode materials are the major problems blocking the practicability of ZIBs.Herein,a high mass-loading and binder-free flexible vanadium oxide(MCV@CC)cathode with a large areal capacity was fabricated via the bridge effect of MXene.The functional MXene bridge induces the growth of the vanadium oxide active layer on the carbon cloth(CC)flexible substrate.The binder-free cathode can reduce the electrochemically inactive weight of the whole electrode,which enhances the energy density of ZIBs.Consequently,the MCV@CC cathode(mass-loading of∼7 mg cm^(−2))delivers a desirable areal capacity(2.36 mAh cm^(−2))and good cycling stability(capacity retention of 86.1%after 1200 cycles at 10 mA cm^(−2)).Moreover,several ex-situ characterization results indicate that the reaction mechanism upon battery cycling is based on the reversible Zn^(2+)/H^(+)(de)intercalation in the vanadium oxide interlayer.Furthermore,the assembled quasi-solid-state MCV@CC//Zn flexible battery exhibits decent performance at different bending states.Such a bridge effect strategy sheds light on the construction of high mass-loading flexible electrodes for ZIBs applications.

Numerical simulation of aerodynamic heating and stresses of chemical vapor deposition ZnS for hypersonic vehicles

Hypersonic vehicles subjected to strong aerodynamic forces and serious aerodynamic heating require more stringent design for an infrared window. In this paper, a finite element analysis is used to present the distributions of thermal and stress fields in the infrared window for hypersonic vehicles based on flowfield studies. A theoretical guidance is provided to evaluate the influence of aerodynamic heating and forces on infrared window materials. The aerodynamic heat flux from Mach 3 to Mach 6 flight at an altitude of 15 km in a standard atmosphere is obtained through flowfield analysis. The thermal and stress responses are then investigated under constant heat transfer coefficient boundary conditions for different Mach numbers. The numerical results show that the maximum stress is higher than the material strength at Mach 6, which means a failure of the material may occur. The maximum stress and temperatures are lower than the material strength and melting point under other conditions, so the material is safe.