查看更多>>摘要：The corrosion behaviors of 2205,2205-Cu,and 2205-Cu-Ce duplex stainless steels(DSSs)were studied under static load in the presence of sulfate-reducing bacteria(SRB).The results demonstrated that the addition of Cu and Ce effectively enhanced the resistance of 2205 DSS to SRB-assisted cracking,and 2205-Cu-Ce DSS exhibited the best corrosion resistance and mechanical properties.The Synergistic addition of Cu and Ce not only inhibited the formation of SRB biofilm but also enhanced the hydrogen-induced cracking resistance of DSSs due to the hydrogen trapping by Cu-rich precipitates.
查看更多>>摘要：The use of Mg-based materials as solid-state hydrogen storage materials can provide a viable solution to the bottleneck hindering the development of hydrogen energy.However,it is necessary to address their excessively stable thermodynamic properties and sluggish kinetic performances.In this study,we prepared a Ni-N-C ternary nanocomposite(designated as Ni@NC)catalyst using Ni-based metal-organic frameworks(Ni-MOFs)as a precursor for catalytic MgH2 hydrogen storage properties.The Ni@NC cata-lyst exhibited excellent promotion effects on the hydrogen absorption and desorption kinetics and the cycling stability of the Mg-based materials.Notably,the composite exhibited room-temperature hydrogen absorption initiation and an onset dehydrogenation temperature of 188 ℃,with complete hydrogenation achieved after holding at 100 ℃ for 60 min.After undergoing 100 cycles of absorption/dehydrogenation,the capacity retention rate was 99.5％.The differential scanning calorimetry(DSC)test results indi-cated that the re-hydrogenated MgH2-Ni@NC composites consist of Mg2NiH4 and MgH2,with corre-sponding dehydrogenation activation energies of 75.2 and 82.9 kJ mol-1 respectively.The mechanism analysis revealed that Ni@NC was uniformly distributed on the MgH2 surface.During dehydrogena-tion/rehydrogenation,Mg2NiH4/Mg2Ni"hydrogen pumping"by Ni and MgH2/Mg occurred in situ,the presence of N-C effectively inhibited the expansion of MgH2/Mg,and the enhanced charge transfer ef-fect was facilitated by N in the Ni@NC composite,synergistically enhancing the kinetic performance and cycling stability of MgH2.
查看更多>>摘要：Nb0.5TiZrV0.5 alloy is one of the lightweight refractory high-entropy alloys(RHEAs)and has a great poten-tial to be structural materials.Here,the microstructural evolution at the grain boundaries(GBs),the ten-sile properties and the deformation mechanism including dislocation and kink evolution of arc-melting(Nb0.5TiZrV0.5)100-xCex RHEAs(at.％,x=0,0.005,0.01,referred to as 0Ce,0.005Ce and 0.01Ce alloys)at room temperature(RT)were systematically investigated.Ce was found to segregate at GBs and the most pronounced grain refinement effect in the 0.005Ce sample.With the Ce content increased from 0.005 at.％to 0.01 at.％,the Ce concentration at GBs increased from 0.12 at.％to～1.17 at.％,subsequently,inducing compositional fluctuation and facilitating transformation of BCC band(V-rich but Zr-poor)to w-like phase with a non-close-packed hexagonal structure(NCPHS,V-and Zr-rich but Ti-poor)at GBs.The 0.005Ce al-loy exhibited the optimized ductility(ef～7.15％)and maintained yield strength of approximately 964 MPa at RT.The better balance of strength-ductility in the 0.005Ce alloy was resulted from synergistic defor-mation of multiple grains,high fraction(55.6％)of movable edge dislocations and abundant kink bands with the most slip systems.However,deteriorating ductility(ef～2.29％)of the Nb0.sTiZrV0.5 alloy with 0.01 at.％Ce addition was mainly attributed to precipitation of the brittle ω-like phase at GBs.These re-sults may provide theoretical and experimental guidance for design of the advanced RHEAs with high specific strength through doping Ce or other rare-earth elements.
查看更多>>摘要：It is essential to promote interfacial separation and charge migration in heterojunctions for effectively driving surface photocatalytic reactions.In this work,we report the construction of a 2D/2D layered BiOIO3/g-C3N4(BIO/CN)heterojunction for photocatalytic NO removal.The BIO/CN heterojunction exhibits a remarkably higher NO photo-oxidation removal rate(46.9％)compared to pristine BIO(20.1％)and CN(25.9％)under visible-light irradiation.Additionally,it effectively suppresses the formation of toxic NO2 intermediates during photocatalytic reaction.The improved photocatalytic performance of BIO/CN com-posite is caused by its S-scheme charge carrier transport mechanism,which is supported by Density Functional Theory simulations of work function and electron density difference,along with in-situ irra-diated X-ray Photoelectron Spectroscopy and Electron Paramagnetic Resonance analyses.This S-scheme structure improves the interfacial carrier separation efficiency and retains the strong photo-redox ability.Our study demonstrates that construction of a S-scheme heterojunction is significant in the design and preparation of highly efficient photocatalysts for air purification.
查看更多>>摘要：To simultaneously improve the microwave absorption and thermal insulation properties of the ceramic materials for stealth high-speed vehicles,layered composites made of polymer-derived SiOC/ZrB2 rein-forced by ZrO2/SiO2 fibers were reported in this work.The composites possess a continuous multilayer structure,which was fabricated via the precursor impregnation assisted by hot press curing and pyrolysis using the transparent ZrO2/SiO2 fibers and polymer-derived SiOC and nano ZrB2.The layered composites show an effective absorption band(EAB)of 4.2 GHz at a thickness of 2.9 mm and a minimum reflection loss of-59.34 dB.The exceptional electromagnetic(EM)wave attenuation capability is ascribed to the impedance matching as well as massive EM wave loss caused by the multilayers in which the nano ZrB2 provides interfacial polarization and electrical conduction loss.With a design of the multi-curvature arch structure,a remarkable reduction of radar cross section can be achieved.Besides,the layered composites exhibit good oxidation resistance and thermal insulation when exposed to the dynamic heating environ-ment,demonstrating the potential application in harsh environments used for multifunctional electro-magnetic absorbing materials.
查看更多>>摘要：Subtle microstructure design and an appropriate multicomponent strategy are essential for advanced electromagnetic absorbing(EMA)materials with a wide effective absorption bandwidth(EAB)and intense absorption.However,sophisticated environments restrict the range of applications for EMA materials.Herein,three hollow spherical bifunctional CoSx/MnS/C nanocomposites with different crystal structures were constructed via cation exchange and subsequent vulcanization.The manganese sulfide and carbon generated during vulcanization exhibit a narrow band gap and enhanced conductivity,thereby facilitating conductive loss.The presence of cobalt sulfide facilitates the improvement of magnetic loss.More impor-tantly,there is a potential difference between different phases at the heterogeneous interface,resulting in a region of space charge,which is conducive to interfacial polarization.The 3D hollow structure and heterogeneous dielectric/magnetic interfaces benefit the predominant EMA performance by forming per-fect impedance matching,interface polarization,conduction loss,and magnetic loss effects.Specifically,an optimal reflection loss(RL)of-51.31 dB at 10.72 GHz and an effective EAB of 5.92 GHz at 2.1 mm can be achieved for Co1-xS/MnS/C nanocomposite.Moreover,the nanocomposites maintained promising self-anticorrosion properties in simulated seawater environments.Transition metal sulfides with supe-rior self-anticorrosion properties provide a pathway to efficient wave-absorbing materials in complicated environments.
查看更多>>摘要：The oxide dispersion strengthening(ODS)high entropy alloy(HEA)exhibits the high elevated temper-ature performance and radiation resistance due to severe atomic lattice distortion and oxide particles dispersed in matrix,which is expected to become the most promising structural material in the next generation of nuclear energy systems.However,microstructure and damage evolution of irradiated ODS HEA under loading remain elusive at submicron scale using the existing simulations owing to a lack of atomic-lattice-distortion information from a micromechanics description.Here,the random field theory informed discrete dislocation dynamics simulations based on the results of high-resolution transmission electron microscopy are developed to study the dislocation behavior and damage evolution in ODS HEA considering the influence of severe lattice distortion and nanoscale oxide particle.Noteworthy,the dam-age behavior shows an unusual trend of the decreasing-to-increasing transition with the continuous load-ing process.There are two main types of damage micromechanics generated in irradiated ODS HEA:the dislocation loop damage in which the damage is controlled by irradiation-induced dislocation loops and their evolution,the strain localization damage in which the damage comes from the dislocation multipli-cation in the local plastic region.The oxide particle hinders the dislocation movement in the main slip plane,and the lattice distortion induces the dislocation sliding to the secondary slip plane,which pro-motes the dislocation cross-slip and dislocation loop annihilation,and thus reduces the material damage in the elastic damage stage.These findings can deeply understand atomic-scale damage mechanism and guide the design of ODS HEA with high radiation resistance.
查看更多>>摘要：Heterostructures of alloyed composites,comprising heterogeneous domains with dramatically different constitutive properties,hold remarkable potential to expand the realm of material design systems and resolve the trade-off between strength and ductility.This study introduces an innovative materials de-sign method for synthesizing gradient pseudo-precipitates heterostructure(GPHS)in non-heat-treatable Al-2.5％Mg alloys.Utilizing cost-effective mild steel as both the diffusion source and protective layer,this heterostructure is achieved through pin-less friction stir-assisted cyclic localized deformation pro-cess.Exogenous Fe atoms diffuse across the interface by friction stir-induced heat conduction,forming Fe-Al second-phase particles in the Al alloy matrix.A rapid inter-diffusion mechanism is activated in conjunction with dense dislocation walls,grain boundaries,and sub-structures,resulting in the forma-tion of pseudo-precipitates.These pseudo-precipitates are ultimately dispersed in a gradient distribution throughout the entire thickness of the Al alloy matrix induced by localized incremental deformation.The GPHSed Al-2.5％Mg alloy exhibits an enhanced synergy of strength and ductility,with a uniform elonga-tion increase from 11％to 21.2％,while maintaining the strength.Multiple strengthening and hardening mechanisms,such as solid solution strengthening,dislocation hardening,and second phase strengthen-ing,work synergistically to promote mechanical performance.Notably,the hetero-deformation between hard pseudo-precipitates and soft Al alloy matrix induces additional strain hardening,leading to high ductility.This work provides a fresh perspective on the design and fabrication of high-performance alloys with advanced heterostructures,especially for non-heat-treatable alloys.
Andrea ToldyDániel István PoórBeáta SzolnokiBoglárka Devecser...
101-111页
查看更多>>摘要：We developed flame retarded polyimine type vitrimers and carbon fibre reinforced composites using two additive and a reactive flame retardant containing phosphorus:ammonium polyphosphate(APP),resor-cinol bis(diphenyl phosphate)(RDP);and N,N',N"-tris(2-aminoethyl)-phosphoric acid triamide(TEDAP).We characterised the vitrimer matrix materials by differential scanning calorimetry(DSC),thermal anal-ysis(TGA),limiting oxygen index(LOI),UL-94 test and mass loss calorimetry(MLC),while the vitrimer composites by LOI,UL-94 test,MLC and dynamic mechanical analysis(DMA).We compared the perfor-mance of the vitrimer systems to a benchmark pentaerythritol-based aliphatic epoxy resin system(PER).The vitrimer reference had higher thermal stability but lower fire performance than the PER aliphatic reference epoxy.At lower phosphorus content,the vitrimer systems exhibited a melting above their vit-rimer transition temperature,which negatively affected their LOI and UL-94 results.From 2％phosphorus content,rapid charring and extinguishing of vitrimers prevented the softening and deforming.The su-perior performance of these same flame retardants in vitrimer systems could be attributed to the high nitrogen content of imine-based vitrimers in combination with phosphorus flame retardants,exploiting nitrogen-phosphorus synergism.In both matrices,flame retardants with solid phase action lead to better fire performance,while in composites,the lowest peak heat release rates(152 kW/m2 in vitrimer com-posite)were achieved with RDP acting predominantly in the gas phase,as carbon fibres hindered the intumescent phenomenon.
查看更多>>摘要：Molybdenum-based metal oxide catalysts are attracting widespread attention in the field of photocatalysis due to their significant applications in addressing energy and environmental challenges.As a new three-dimensional molybdenum-based metal oxide photocatalyst,NaZn2(OH)(MoO4)2·H2O is highly promising as a semiconductor catalyst for enhancing photocatalytic performance,thanks to its ease of preparation and environmental friendliness.Herein,we prepared an S-scheme heterojunction photocatalyst composed of NaZn2(OH)(MoO4)2·H2O and CdS,which enabled efficient H2 production through photocatalysis,ad-dressing issues associated with the rapid recombination rate of photogenerated carriers.The hydrogen generation yield of NZM/CdS-30 reached 5335 μmol g-1 h-1,approximately 30 and 953 times higher than those of CdS and NaZn2(OH)(MoO4)2·H2O,respectively.Moreover,we verified the mechanism through in-situ XPS analysis to elucidate the activity enhancement.Our research provides an innovative universal and effective synthetic strategy of design S-scheme heterojunction for hydrogen production from solar water splitting.
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