查看更多>>摘要：Nature-inspired superhydrophobic coatings with typical Cassie-Baxter contacts garner numerous interests for multifunctional applications.However,undesirable poor mechanical and thermal stability are still crucial bottlenecks for real-world employment.This work introduces a cost-effective,fluorine free and versatile strategy to achieve double-layered PDMS agglutinated candle soot coating with superior water-repellent superhydrophobicity.The surface morphologies,chemical compositions and wettability behaviors were investigated in detail.The mechanical stability,chemical stability and durable corrosion resistance of the fabricated PDMS-CS coating were evaluated through friction,calcination and electrochemical impedance spectroscopy.The results demonstrate a remarkably enhanced mechanical robustness and corrosion resistance,indicating PDMS units can act as an effective agglutinating agent between candle soot and underlying substrate.The synergistic effect of PDMS agglutination,porous network nanostructures and extremely low surface energy of incomplete combustion induced candle soot deposition contribute to the eventually robust corrosion resisting coating,which greatly increases the possibility for practical applications.
查看更多>>摘要：The corrosion of mild steels by liquid aluminum is an intractable issue in aluminum industry.This review aims to provide an overview of the corrosion behavior of mild steels in the static liquid aluminum with an emphasis on the thermodynamic and kinetic aspects.The corrosion mechanisms of mild steels in liquid aluminum are discussed systematically,based on which four corrosion control approaches including alloying,introducing secondary phase,matrix microstructure control and surface treatment are introduced.Currently,a combination of improvement approaches may have a great potential for further enhancement in corrosion resistance.
查看更多>>摘要：In this work,carbon nanotube (CNT) based nanocomposites with high mass fraction are proposed by in-situ bridging carbon matrix into CNT paper through optimized chemical vapor infiltration (CVI).Nanoinfiltration behavior of CNTs is basically investigated under the CVI process.The contact between each CNT can be strengthened and the conductive pathways can be established,resulting in the better mechanical and electrical properties.Compared with the pristine CNT paper,the CNT/C composite after pyrolysis process confirms a remarkable advance in tensile strength (up to 310 ± 13 MPa) and Young's modulus (up to 2.4 ± 0.1 GPa).Besides,a notable feature of electrical conductivity also shows an improvement up to 8.5 S/cm,which can be attributed to the mass fraction of CNT (41 wt％) breaking the limits of percolation thresholds and the efficient densification of this sample to establish the conductive pathways.This study has a broad application in the development of the multi-functional electrical and engineering materials.
查看更多>>摘要：A well designed coating for polyetheretherketone (PEEK) implants can provide enough support to overcome crucial medical challenges,which are insufficient osseointegration and high rate of infection.Herein,we utilize the co-deposition of polydopamine (PDA) and copper-citrate nanoclusters to construct a pH-responsive coating on porous PEEK for synergistic bone regeneration,vascular formation and anti-infection.Specifically,this PDA coating released high dose of copper and citrate at lower pH value,which increased intracellular copper content,boosted production of reactive oxygen species and severe damage of protein,leading to killing of 93 ％ planktonic bacterial and eradication of adherent bacteria.At pH of 7.4,the release of copper and citrate were in a slow and sustained behavior,synergistically enhanced vascular formation potential and osteodiffereration of Ad-MSC in vitro.After implanted in rabbit tibia for 6 and 12 weeks,the micro-CT evaluation and histological analysis consistently highlighted the ability of this PDA coating to increase new bone formation adjacent to coated PEEK implant and enhance bone-implant interfacial integration.These results were proven to be related to the synergistic effect that citrate facilitated a 2-fold influx of copper into cells,which not only enhanced the bacteria-killing ability but also encouraged bone regeneration of implants.This present work provides an effective method to control infections while promoting osseointegration simultaneously,which will show tremendous clinical application and can be a solution to current challenges facing orthopedics.
查看更多>>摘要：Cyclic oxidation behavior of NiCrAlYSi + NiAl/cBN abrasive coating at 900 ℃ and the mechanical properties of the coating-substrate system were investigated.Results indicated that elemental interdiffusion occurred between the coating and substrate,which caused the formation of interdiffusion zone (IDZ) and second ary reaction zone (SRZ) during aluminization,while their compositions and structures changed with oxidation.AlN interfacial layer formed at cBN/metallic matrix interface during aluminization,while it transformed into multilayer oxides during oxidation.Due to the microstructural evolution of these interfaces,the fracture behavior and bending toughness of the system changed greatly during three-point bending tests.Besides,the damage mechanisms were discussed.
查看更多>>摘要：SiC nanowires/pyrocarbon (SiCnws/PyC) core-shell structure toughened C/C-ZrC-SiC composites were fabricated by CLVD process,and the influences of PyC shell thickness on the microstructure and ablation resistance of the composites were researched.The results presented that SiCnws/PyC core-shell structure had a linear shape,and the composites became dense with the increasing PyC thickness.When the thickness of PyC shell increased from 0 to 2.4 μm,the density and thermal conductivity of the composites was improved gradually,but the coefficient of thermal expansion (CTE) decreased firstly and then increased.After the ablation test for 90 s,the ablation rates of the composites decreased continuously as the PyC thickness increased from 0 to 1.4 μm,but increased when the PyC thickness was up to 2.4 μm.Especially when the PyC thickness was 1.4 μm,the linear and mass ablation rates of the composites were 71.25 ％ and 63.01 ％ lower than those of the composites without PyC shell.The reasons behind the remarkable improvement of anti-ablation property were that the proper PyC thickness could alleviate the CTE mismatch to promote the formation of complete oxide coating,improve the thermal conductivity to reduce heat corrosion and enhance the capability to limit the mechanical erosion.
查看更多>>摘要：Interfacial design is one of the most promising ways in improving mechanical properties of nanocomposites.In this work,a multifunctional aerogel with excellent mechanical performances,sensing sensitivity,and fire retardancy is fabricated by taking advantage of metal coordination between biopolymer and Fe3+.Montmorillonite (MMT) nanosheets are added to induce a 'brick and mortar' structure.The coordination remarkably reduces structural defects,leading to well-formed lamellas that can effectively distribute stress under sever compression without plastic deformation.The structural merits impart the aerogel highly reversible compressibility even at 99 ％ strain and superior durability.Besides,it demonstrates high sensing performance in wearable health monitoring devices,and shows fire resistance property that can maintain elasticity in a flame.The work offers a facile and effective method to create multifunctional aerogels from various polymers.
查看更多>>摘要：This work focuses on irradiation behaviors of a novel silicon carbide and carbon coated nanostructured ferritic alloy (SiC-C@NFA) composite for potential applications as a cladding and structural material for next generation nuclear reactors.The SiC-C@NFA samples were irradiated with 1 MeV Kr ions up to 10 dpa at 300 and 450 ℃.Microstructures and defect evolution were studied in-situ at the IVEM-Tandem facility at Argonne National Laboratory.The effects of ion irradiation on various phases such as α-ferrite matrix,(Fe,Cr)7C3,and (Ti,W)C precipitates were evaluated.The α-ferrite matrix showed a continuous increase in dislocation density along with spatial ordering of dislocation loops (or loop strings) at ＞5 dpa.The size of the dislocation loops at 450 ℃ was larger than that at 300 ℃.The nucleation and growth of new (Ti,W)C precipitates in α-ferrite grains were enhanced with the ion dose at 450 ℃.This study provides new insight into the irradiation resistance of the SiC-C@NFA system.
查看更多>>摘要：Here,we report the leading manufacture of the large-scale integral weldless stainless steel forging ring (ψ =15.6 m) by the multilayer additive hot-compression bonding technology.Moreover,the detailed interface healing mechanism involving interfacial oxide evolution is elucidated,which validates the feasibility and reliability of the technique we proposed.
Hyun Ji KimSang-Cheol JinJae-Gil JungSung Hyuk Park...
87-97页
查看更多>>摘要：This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg-7Sn-1Al-1Zn (TAZ711) alloy on the dynamic recrystallization (DRX) behavior during hot extrusion at low and high temperatures and the resultant microstructure and mechanical properties of the alloy.To this end,partially homogenized (PH) and fully homogenized (FH) billets are extruded at temperatures of 250 and 450 ℃.The PH billet contains fine and coarse undissolved Mg2Sn particles in the interdendritic region and along the grain boundaries,respectively.The fine particles (＜1 μm in size) retard DRX during extrusion at 250 ℃ via the Zener pinning effect,and this retardation causes a decrease in the area fraction of dynamically recrystallized (DRXed) grains of the extruded alloy.In addition,the inhomogeneous distribution of fine particles in the PH billet leads to the formation of a bimodal DRXed grain structure with excessively grown grains in particle-scarce regions.In contrast,in the FH billet,numerous nanosized Mg2Sn precipitates are formed throughout the material during extrusion at 250 ℃,which,in turn,leads to the formation of small,uniform DRXed grains by the grain-boundary pinning effect of the precipitates.When the PH billet is extruded at the high temperature of 450 ℃,the retardation effect of the fine particles on DRX is weakened by their dissolution in the α-Mg matrix and the increased extent of thermally activated grain-boundary migration.In contrast,the coarse Mg2Sn particles in the billet promote DRX during extrusion through the particle-stimulated nucleation phenomenon,which results in an increase in the area fraction of DRXed grains.At both low and high extrusion temperatures,the extruded material fabricated using the PH billet,which contains both fine and coarse undissolved particles,has a lower tensile strength than that fabricated using the FH billet,which is virtually devoid of second-phase particles.This lower strength of the former is attributed mainly to the larger grains and/or absence of nanosized M2Sn precipitates in it.
NETL
NSTL
维普
万方数据