Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality...Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality.It is essential to understand the underlying printability of different material combinations based on an adapted process.Here,the printability disparities of two common and attractive material combinations(nickel-and iron-based alloys)are evaluated at the macro and micro levels via laser directed energy deposition(DED).The deposition processes were captured using in situ high-speed imaging,and the dissimilarities in melt pool features and track morphology were quantitatively investigated within specific process windows.Moreover,the microstructure diversity of the tracks and blocks processed with varied material pairs was comparatively elaborated and,complemented with the informative multi-physics modeling,the presented non-uniformity in mechanical properties(microhardness)among the heterogeneous material pairs was rationalized.The differences in melt flow induced by the unlike thermophysical properties of the material pairs and the resulting element intermixing and localized re-alloying during solidification dominate the presented dissimilarity in printability among the material combinations.This work provides an in-depth understanding of the phenomenological differences in the deposition of dissimilar materials and aims to guide more reliable DED forming of bimetallic parts.展开更多
Thermal barrier coatings(TBCs)are extensively utilized in aero-engines and heavy-duty gas turbines due to their outstanding properties,including low thermal conductivity,corrosion,high-temperature oxidation,and wear r...Thermal barrier coatings(TBCs)are extensively utilized in aero-engines and heavy-duty gas turbines due to their outstanding properties,including low thermal conductivity,corrosion,high-temperature oxidation,and wear resistance.The rising thrust-to-weight ratio and service temperature in engine hot sections have presented a significant challenge in TBC's materials,structure,and preparation process;it is one of the current research hotspots in the aviation field.This paper reviews the recent advancement in turbine blade TBCs.It focuses on the TBC's structure,deposition mechanism and the key performance evaluation indexes for TBCs applied to turbine blades.Finally,the future research field of TBCs for turbine blades is also be prospected.展开更多
In 2023,pivotal advancements in artificial intelligence(AI)have significantly experienced.With that in mind,traditional methodologies,notably the p-y approach,have struggled to accurately model the complex,nonlinear s...In 2023,pivotal advancements in artificial intelligence(AI)have significantly experienced.With that in mind,traditional methodologies,notably the p-y approach,have struggled to accurately model the complex,nonlinear soil-structure interactions of laterally loaded large-diameter drilled shafts.This study undertakes a rigorous evaluation of machine learning(ML)and deep learning(DL)techniques,offering a comprehensive review of their application in addressing this geotechnical challenge.A thorough review and comparative analysis have been carried out to investigate various AI models such as artificial neural networks(ANNs),relevance vector machines(RVMs),and least squares support vector machines(LSSVMs).It was found that despite ML approaches outperforming classic methods in predicting the lateral behavior of piles,their‘black box'nature and reliance only on a data-driven approach made their results showcase statistical robustness rather than clear geotechnical insights,a fact underscored by the mathematical equations derived from these studies.Furthermore,the research identified a gap in the availability of drilled shaft datasets,limiting the extendibility of current findings to large-diameter piles.An extensive dataset,compiled from a series of lateral loading tests on free-head drilled shaft with varying properties and geometries,was introduced to bridge this gap.The paper concluded with a direction for future research,proposes the integration of physics-informed neural networks(PINNs),combining data-driven models with fundamental geotechnical principles to improve both the interpretability and predictive accuracy of AI applications in geotechnical engineering,marking a novel contribution to the field.展开更多
A feasible approach to rectify the world's energy demand using sustainable development of adequate energy generation and storage technologies in a single channel.In this respect,we made a holistic approach with a ...A feasible approach to rectify the world's energy demand using sustainable development of adequate energy generation and storage technologies in a single channel.In this respect,we made a holistic approach with a bifunctional electrode material to perform effectively in energy generation and storage applications.MoS_(2) nanosheets were produced by the eco-friendly method and reduced graphene oxide is used to prepared by carbon soot which is derived from castor oil.The prepared soot and rGO were combined with MoS_(2) nanosheets using a simple sonication method.The as-prepared sample was introduced in the supercapacitor and DSSC application.The combination MoS_(2)@rGO provides an enhanced conversion efficiency of 11.81%and the reproducibility of DSSC is also studied.Further,MoS_(2)@rGO is used to fabricate an asymmetric supercapacitor to investigate its real-time application.The device produced the maximum power density(1666.6 mW/kg)and energy density(25.69 mWh/Kg)at 1 A/g.The asymmetric supercapacitor device holds a cyclic stability of 81.4%for 5000 cycles and it powered up an LED device for 4 min.展开更多
Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic co...Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic coatings is systemically examined by experimental shear force measurements and theoretical methods.The mechanical factor-elastic modulus of the coatings greatly dictates the hydrate AS,which is explained by the adhesion mechanics theory,beyond the usual factors such as wettability and structural roughness.Moreover,the hydrate AS increases with reducing the thickness of the elastic coatings,resulted from the decrease of the apparent surface elastic modulus.The effect of critical thickness for the elastic materials with variable elastic modulus on the hydrate AS is also revealed.This study provides deep perspectives on the regulation of the hydrate AS by the elastic modulus of elastic materials,which is of significance to design anti-hydrate surfaces for mitigation of hydrate accretion in petro-pipelines.展开更多
In this work,texturing is proposed to improve the piezoelectric response of PSN-PMN-PT ceramics.The PSN-PMN-PT textured ceramic with a Lotgering factor F001 higher than 99%was synthesized by the liquid-phase-assisted ...In this work,texturing is proposed to improve the piezoelectric response of PSN-PMN-PT ceramics.The PSN-PMN-PT textured ceramic with a Lotgering factor F001 higher than 99%was synthesized by the liquid-phase-assisted template grain growth(TGG)method.The addition of CuO/B2 O3 sintering aids improves the BT templates induced grain orientation growth behavior significantly.In comparison with its random counterpart,the Cu/B-T textured ceramic exhibits a high Lotgering factor F001 of 99%and significantly enhanced dielectric and piezoelectric responses:ε_(r)~3100,tanδ~0.8%,d_(33)~1030 pC N^(-1),d_(33)·g_(33)~34.2×10^(-12) m^(2) N^(-1),d_(33)∗~1490 pm V^(-1)@5 kV cm^(-1),Smax~0.26%@20 kV cm^(-1) and H_(s)~8.5%.In the meantime,good temperature stability is observed in the Cu/B-T textured ceramic with a variation of d_(33)∗@20 kV cm^(-1) and annealed d_(33) lower than 9.68%and 18.1%over a wide temperature range of 25-140°C.This work shows that PSN-PMN-PT textured ceramic(Cu/B-T)has great potential for electrome-chanical device applications such as precision actuators,ultrasound transducers,and energy harvesters.展开更多
Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance;their appreciable mechanical,corrosive,and biocompatible properti...Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance;their appreciable mechanical,corrosive,and biocompatible properties are highly sought after for lightweight and high-strength load-bearing orthopedic and dental implants.Examples of such porous materials are metals,ceramics,and polymers.Although,easy to manufacture and lightweight,porous polymers do not inherently exhibit the required mechanical strength for hard tissue repair or replacement.Alternatively,porous ceramics are brittle and do not possess the required fatigue resistance.On the other hand,porous biocompatible metals have shown tailorable strength,fatigue resistance,and toughness.Thereby,a significant interest in investigating the manufacturing challenges of porous metals has taken place in recent years.Past research has shown that once the advantages of porous metallic structures in the orthopedic implant industry have been realized,their biological and biomechanical compatibility—with the host bone—has been followed up with extensive methodical research.Various manufacturing methods for porous or functionally graded metals are discussed and compared in this review,specifically,how the manufacturing process influences microstructure,graded composition,porosity,biocompatibility,and mechanical properties.Most of the studies discussed in this review are related to porous structures for bone implant applications;however,the understanding of these investigations may also be extended to other devices beyond the biomedical field.展开更多
Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aeroge...Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.展开更多
In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ an...In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ and under strain rates of 0.001-1 s^-1. The flow stress curves show that the DRX is responsible for flow softening during hot compression. The effects of temperature and strain rate on the strain and stress corresponding to peak point （εp and σp） of flow curve were analyzed individually. It is realized that, they increase with strain rate and decrease with temperature. The relationship between Zener-Hollomon parameter （Z） and εp was investigated and the equation of εp=4.3×10^-4^0.14 was proposed. The strain for the maximum rate of DRX （εmax） was determined under different deformation conditions. Therefore, it is realized that it increases with Z parameter and vise versa. On the basis of obtained results, the equation of εmax=9.5 × 10^-4Z0.12 was proposed.展开更多
Molecular dynamics(MD)simulations of the titanium-graphene nanocomposites(TiGNCs)under uniaxial tension are carried out to investigate the mechanical properties and reinforcement mechanism of graphene in composites.It...Molecular dynamics(MD)simulations of the titanium-graphene nanocomposites(TiGNCs)under uniaxial tension are carried out to investigate the mechanical properties and reinforcement mechanism of graphene in composites.It is found that introduction of mechanically robust graphene limits the strain-induced dislocation and araorphization and thereby highly improves the mechanical properties of metallic titanium that are greatly affected by the crystal stacking orientation of graphene and titanium layers.The thickness of titanium layers,interface interaction and working temperature play an important role in the mechanical strength and elastic moduli of composites.The results show the mechanical properties of TiGNCs are monotonically enhanced with reduction of the titanium layer thickness and working temperature,and the Young5s modulus obtained by MD simulation are higher than that predicted by the rule of mixture(ROM)due to consideration of interfacial interaction in computational calculation.In addition,once the critical thickness of titanium layer is reached,graphene wrinkles are induced in composites because of Poisson's effect induced large lateral compression stress in the interface region.This study provides helpful insights into fundamental understanding reinforcing mechanism of graphene and ultimately contribute to the optimal design and performance of mechanically robust graphene-based metallic composites.展开更多
The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance metho...The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance methods. Inhibition efficiency （IE）, corrosion rate and surface coverage were evaluated at different concentrations of BBTS. The results of the investigation showed that this compound had good inhibiting properties for mild steel corrosion in hydrochloric acid and BBTS was a mixed-type inhibitor. BBTS chemisorbed at the electrode surface obeyed Langmuir adsorption isotherm and formed a stable surface complex on the mild steel surface. The synergistic effect of halide ion in acid solution suggested a co-adsorption of BBTS inhibitor by the adsorbed iodide ion.展开更多
BaTiO_(3)ceramics are difficult to withstand high electric fields,so the energy storage density is relatively low,inhabiting their applications for miniaturized and lightweight power electronic devices.To address this...BaTiO_(3)ceramics are difficult to withstand high electric fields,so the energy storage density is relatively low,inhabiting their applications for miniaturized and lightweight power electronic devices.To address this issue,we added Sr_(0.7)Bi_(0.2)TiO_(3)(SBT)into BaTiO_(3)(BT)to destroy the long-range ferroelectric domains.Ca^(2+)was introduced into BT-SBT in the form of CaTiO_(3)(CT),which has the effect of inhibiting the movement of A-site defects to reduce dielectric loss and refining the grains to increase the breakdown field strength.In addition,we have increased the density and grain uniformity of ceramics by repeated rolling of the green samples through the viscous polymer processing(VPP),to further increase the breakdown electric field.The BT-SBT-CT ceramics exhibit the high recoverable energy storage density of 4.0 J·cm^(-3)under electric field of 480 kV·cm^(-1).Its recoverable energy storage density varies by less than 8%in the temperature range of 30-150℃,indicating good temperature stability of the energy storage performance.In this work,the energy storage performance of barium titanate-based ceramics was greatly improved by transforming ferroelectrics into relaxor ferroelectrics and VPP method,which can bring new inspiration for the research of energy storage ceramics.展开更多
Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures...Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures and textures of porous glass-ceramics are investigated by using differential thermogravimetric analysis/differential thermal analysis ( TGA/SDTA) ,X-ray diffraction ( XRD) ,and scanning electron microsco- py ( SEM) . The activity energy of crystallization ( E) and crystallization kinetics parameter ( k) were calculated based on the modified JMA equation. The Avrami parameter n was obtained according to Augis-Bennett function. The results show that the k value of No. 1 sample ( SiO2 /CaO = 61∶ 18) is the largest among all samples, which tends to crystallize more easily,and crystallization processes of all samples are observed bulk crystallization. The main crystal phase observed is parawollastonite ( clinorhombic system) with puncheon shape. Poreforming agents decomposed at 100 - 500 ℃ form a large number of closed pores with micron dimension and several semi-open pores distribute uniformly in the glass-ceramics matrix. This work may be expected to be favorable for industrial scale applications of porous glass-ceramics in the field of building thermal insulation.展开更多
Zinc borate(ZB)particles dispersed in silicone oil(SO)at concentrations of φ=5vol%-20vol% were subjected to dielectric analysis to elucidate their polarization strength,time,and mechanism.Results revealed that all vi...Zinc borate(ZB)particles dispersed in silicone oil(SO)at concentrations of φ=5vol%-20vol% were subjected to dielectric analysis to elucidate their polarization strength,time,and mechanism.Results revealed that all virgin dispersions lacked polarization.Triton X-100,a non-ionic surfactant,was added to ZB/SO dispersions to enhance the polarizability of ZB particles.The addition of 1vol% Triton X-100 enhanced the polarizability of ZB/SO dispersions,and the 15vol% ZB/SO system provided the highest dielectric difference Δε′(the difference in ε′values at zero and infinite frequency,Δε′=ε0–ε∝)of 3.64.The electrorheological(ER)activities of the ZB/SO/Triton-X dispersion system were determined through the ER response test,and viscoelastic behaviors were investigated via oscillation tests.A recoverable deformation of 36% under an applied electrical field strength of 1.5 kV/mm was detected through creep and creep recovery tests.展开更多
In this work, the use of computational methods was essential to distinguish the three possible isomeric structures of the [RuCl3(H2O)2(Gly)] molecule. The characterization of these molecules was performed using IR, NM...In this work, the use of computational methods was essential to distinguish the three possible isomeric structures of the [RuCl3(H2O)2(Gly)] molecule. The characterization of these molecules was performed using IR, NMR and UV-VIS simulations. Some calculations related to the optimization of structures and properties such as chemical hardness and dipole moment were also conducted. The fac-cis isomer presented promising data when compared to the experimental data, indicating that this is the likely experimentally synthesized isomer. This study demonstrates the technical utility of the computational calculations by virtue of situations that prevent the realization of X-ray diffraction.展开更多
Electrorheological properties and creep-recovery behavior of polythiophene/polyoxymethylene-blend having PT（50%）/POM（50%） composition were investigated.Particle size,conductivity and dielectric values were measure...Electrorheological properties and creep-recovery behavior of polythiophene/polyoxymethylene-blend having PT（50%）/POM（50%） composition were investigated.Particle size,conductivity and dielectric values were measured to be 24.77μm,3.85×10^（-5） S·m^（-1） and 26.75,respectively.Sedimentation ratio was measured to be 64%at the end of 16 days.The effects of dispersed particle volume fraction,external electric field strength,shear rate,frequency and temperature on ER properties and storage modulus of PT/POM-blend/silicone oil（SO） suspensions were examined.Enhancement were observed in the electric field viscosities of the suspensions and thus they were classified as a smart material.Shear thinning non-Newtonian viscoelastic behavior was determined for PT/POM-blend/SO system.Further,time-dependent deformation was examined by creep-recovery tests and recoverable viscoelastic deformation established.展开更多
Film dielectric capacitors enabled with large breakdown field strength and high energy density play a key role for compact and integrated power systems.Nevertheless,the energy storage efficiency is always sacrificed a...Film dielectric capacitors enabled with large breakdown field strength and high energy density play a key role for compact and integrated power systems.Nevertheless,the energy storage efficiency is always sacrificed as we tried to increase the energy density.This trade-off between energy density and efficiency means significant energy dissipation and thermal effects,which will lead to a deterioration ofthe reliability and lifetime of the dielectric capacitors.展开更多
Castor oil is used to synthesize phenolic resin modified polyol. Castor oil, phenolic resin were taken in the molar ratio 0.07：0.027 and diethylene glycol （DEG） was also taken in varying hydroxyl numbers to achieve...Castor oil is used to synthesize phenolic resin modified polyol. Castor oil, phenolic resin were taken in the molar ratio 0.07：0.027 and diethylene glycol （DEG） was also taken in varying hydroxyl numbers to achieve chemical modification in the backbone of synthesized polyol. Physico-chemical properties like acid value, OH value and moisture content of the modified polyol were measured. The prepared phenolic resin blended polyol were reacted with 4, 4-methylene diisocyanate and 2, 4-toluene diisocyanate to formulate the two component polyurethane （PU） coatings. Prepared coating is used to study properties such as gel time, surface dry, tack free and hard surface drying times. It was found that phenolic resin and diethyleneglycol used in synthesizing castor oil based modified polyols show the significant changes in physico-chemical properties of synthesized polyols. The variation in physico-chemical properties of synthesized polyol provide the information for desirable curing of polyurethane systems.展开更多
基金supported by the National Natural Science Foundation of China(51975112,52375412)Fundamental Research Funds for Central Universities(N2203011)。
文摘Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality.It is essential to understand the underlying printability of different material combinations based on an adapted process.Here,the printability disparities of two common and attractive material combinations(nickel-and iron-based alloys)are evaluated at the macro and micro levels via laser directed energy deposition(DED).The deposition processes were captured using in situ high-speed imaging,and the dissimilarities in melt pool features and track morphology were quantitatively investigated within specific process windows.Moreover,the microstructure diversity of the tracks and blocks processed with varied material pairs was comparatively elaborated and,complemented with the informative multi-physics modeling,the presented non-uniformity in mechanical properties(microhardness)among the heterogeneous material pairs was rationalized.The differences in melt flow induced by the unlike thermophysical properties of the material pairs and the resulting element intermixing and localized re-alloying during solidification dominate the presented dissimilarity in printability among the material combinations.This work provides an in-depth understanding of the phenomenological differences in the deposition of dissimilar materials and aims to guide more reliable DED forming of bimetallic parts.
基金supported by the National Natural Science Foundation of China(Grant No.52271087).
文摘Thermal barrier coatings(TBCs)are extensively utilized in aero-engines and heavy-duty gas turbines due to their outstanding properties,including low thermal conductivity,corrosion,high-temperature oxidation,and wear resistance.The rising thrust-to-weight ratio and service temperature in engine hot sections have presented a significant challenge in TBC's materials,structure,and preparation process;it is one of the current research hotspots in the aviation field.This paper reviews the recent advancement in turbine blade TBCs.It focuses on the TBC's structure,deposition mechanism and the key performance evaluation indexes for TBCs applied to turbine blades.Finally,the future research field of TBCs for turbine blades is also be prospected.
基金supported by Prince Sultan University(Grant No.PSU-CE-TECH-135,2023).
文摘In 2023,pivotal advancements in artificial intelligence(AI)have significantly experienced.With that in mind,traditional methodologies,notably the p-y approach,have struggled to accurately model the complex,nonlinear soil-structure interactions of laterally loaded large-diameter drilled shafts.This study undertakes a rigorous evaluation of machine learning(ML)and deep learning(DL)techniques,offering a comprehensive review of their application in addressing this geotechnical challenge.A thorough review and comparative analysis have been carried out to investigate various AI models such as artificial neural networks(ANNs),relevance vector machines(RVMs),and least squares support vector machines(LSSVMs).It was found that despite ML approaches outperforming classic methods in predicting the lateral behavior of piles,their‘black box'nature and reliance only on a data-driven approach made their results showcase statistical robustness rather than clear geotechnical insights,a fact underscored by the mathematical equations derived from these studies.Furthermore,the research identified a gap in the availability of drilled shaft datasets,limiting the extendibility of current findings to large-diameter piles.An extensive dataset,compiled from a series of lateral loading tests on free-head drilled shaft with varying properties and geometries,was introduced to bridge this gap.The paper concluded with a direction for future research,proposes the integration of physics-informed neural networks(PINNs),combining data-driven models with fundamental geotechnical principles to improve both the interpretability and predictive accuracy of AI applications in geotechnical engineering,marking a novel contribution to the field.
基金financial support by MHRD-SPARC-890(2019)UAE for financial support+1 种基金the full financial support by MHRD-SPARC-890(2019)the instrumentation facility utilized from RUSA 2.0 grant No.F.24-51/2014-U,Policy(TNMultiGen)Govt of India Projects。
文摘A feasible approach to rectify the world's energy demand using sustainable development of adequate energy generation and storage technologies in a single channel.In this respect,we made a holistic approach with a bifunctional electrode material to perform effectively in energy generation and storage applications.MoS_(2) nanosheets were produced by the eco-friendly method and reduced graphene oxide is used to prepared by carbon soot which is derived from castor oil.The prepared soot and rGO were combined with MoS_(2) nanosheets using a simple sonication method.The as-prepared sample was introduced in the supercapacitor and DSSC application.The combination MoS_(2)@rGO provides an enhanced conversion efficiency of 11.81%and the reproducibility of DSSC is also studied.Further,MoS_(2)@rGO is used to fabricate an asymmetric supercapacitor to investigate its real-time application.The device produced the maximum power density(1666.6 mW/kg)and energy density(25.69 mWh/Kg)at 1 A/g.The asymmetric supercapacitor device holds a cyclic stability of 81.4%for 5000 cycles and it powered up an LED device for 4 min.
基金This work is financially supported by the Key Laboratory of Icing and Anti/De-icing of CARDC(Grant No.IADL20210402)the National Natural Science Foundation of China(Grant Nos.12002350,12172314,11772278 and 11904300)+1 种基金the Jiangxi Provincial Outstanding Young Talents Program(Grant No.20192BCBL23029)the Fundamental Research Funds for the Central Universities(Xiamen University:Grant No.20720210025).
文摘Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic coatings is systemically examined by experimental shear force measurements and theoretical methods.The mechanical factor-elastic modulus of the coatings greatly dictates the hydrate AS,which is explained by the adhesion mechanics theory,beyond the usual factors such as wettability and structural roughness.Moreover,the hydrate AS increases with reducing the thickness of the elastic coatings,resulted from the decrease of the apparent surface elastic modulus.The effect of critical thickness for the elastic materials with variable elastic modulus on the hydrate AS is also revealed.This study provides deep perspectives on the regulation of the hydrate AS by the elastic modulus of elastic materials,which is of significance to design anti-hydrate surfaces for mitigation of hydrate accretion in petro-pipelines.
基金supported by the National Natural Science Foun-dation of China under Grant No.11704249the Natural Science Foundation of Shaanxi Provincial Department of Education under Grant No.20JK0667the President’s Fund of Xi’an Technologi-cal University under Grant No.XGPY200204.
文摘In this work,texturing is proposed to improve the piezoelectric response of PSN-PMN-PT ceramics.The PSN-PMN-PT textured ceramic with a Lotgering factor F001 higher than 99%was synthesized by the liquid-phase-assisted template grain growth(TGG)method.The addition of CuO/B2 O3 sintering aids improves the BT templates induced grain orientation growth behavior significantly.In comparison with its random counterpart,the Cu/B-T textured ceramic exhibits a high Lotgering factor F001 of 99%and significantly enhanced dielectric and piezoelectric responses:ε_(r)~3100,tanδ~0.8%,d_(33)~1030 pC N^(-1),d_(33)·g_(33)~34.2×10^(-12) m^(2) N^(-1),d_(33)∗~1490 pm V^(-1)@5 kV cm^(-1),Smax~0.26%@20 kV cm^(-1) and H_(s)~8.5%.In the meantime,good temperature stability is observed in the Cu/B-T textured ceramic with a variation of d_(33)∗@20 kV cm^(-1) and annealed d_(33) lower than 9.68%and 18.1%over a wide temperature range of 25-140°C.This work shows that PSN-PMN-PT textured ceramic(Cu/B-T)has great potential for electrome-chanical device applications such as precision actuators,ultrasound transducers,and energy harvesters.
基金supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Number R01 AR067306-01 and R01 AR078241(PI—Bandyopadhyay)。
文摘Porous and functionally graded materials have seen extensive applications in modern biomedical devices—allowing for improved site-specific performance;their appreciable mechanical,corrosive,and biocompatible properties are highly sought after for lightweight and high-strength load-bearing orthopedic and dental implants.Examples of such porous materials are metals,ceramics,and polymers.Although,easy to manufacture and lightweight,porous polymers do not inherently exhibit the required mechanical strength for hard tissue repair or replacement.Alternatively,porous ceramics are brittle and do not possess the required fatigue resistance.On the other hand,porous biocompatible metals have shown tailorable strength,fatigue resistance,and toughness.Thereby,a significant interest in investigating the manufacturing challenges of porous metals has taken place in recent years.Past research has shown that once the advantages of porous metallic structures in the orthopedic implant industry have been realized,their biological and biomechanical compatibility—with the host bone—has been followed up with extensive methodical research.Various manufacturing methods for porous or functionally graded metals are discussed and compared in this review,specifically,how the manufacturing process influences microstructure,graded composition,porosity,biocompatibility,and mechanical properties.Most of the studies discussed in this review are related to porous structures for bone implant applications;however,the understanding of these investigations may also be extended to other devices beyond the biomedical field.
文摘Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.
文摘In this research, the dynamic recrystallization （DRX） behavior of an as-cast precipitation hardenable （PH） stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ and under strain rates of 0.001-1 s^-1. The flow stress curves show that the DRX is responsible for flow softening during hot compression. The effects of temperature and strain rate on the strain and stress corresponding to peak point （εp and σp） of flow curve were analyzed individually. It is realized that, they increase with strain rate and decrease with temperature. The relationship between Zener-Hollomon parameter （Z） and εp was investigated and the equation of εp=4.3×10^-4^0.14 was proposed. The strain for the maximum rate of DRX （εmax） was determined under different deformation conditions. Therefore, it is realized that it increases with Z parameter and vise versa. On the basis of obtained results, the equation of εmax=9.5 × 10^-4Z0.12 was proposed.
基金supported by the National Natural Science Foundation of China(Grants U1737106,51705411,11772278 and 11502221)the Jiangxi Provincial Outstanding Young Talents Program(Grant 20192BCBL23029)+4 种基金the Fundamental Research Funds for the Central Universities(Xiamen University:Grants 20720180014,20720180018 and 20720160088)Shaanxi Provincial Natural Science Foundation(Grant 2018JM5022)Fujian Provincial Department of Science&Technology(Grant 2017J05028)“111”Project(Grant B16029)the 1000 Talents Program from Xiamen University.
文摘Molecular dynamics(MD)simulations of the titanium-graphene nanocomposites(TiGNCs)under uniaxial tension are carried out to investigate the mechanical properties and reinforcement mechanism of graphene in composites.It is found that introduction of mechanically robust graphene limits the strain-induced dislocation and araorphization and thereby highly improves the mechanical properties of metallic titanium that are greatly affected by the crystal stacking orientation of graphene and titanium layers.The thickness of titanium layers,interface interaction and working temperature play an important role in the mechanical strength and elastic moduli of composites.The results show the mechanical properties of TiGNCs are monotonically enhanced with reduction of the titanium layer thickness and working temperature,and the Young5s modulus obtained by MD simulation are higher than that predicted by the rule of mixture(ROM)due to consideration of interfacial interaction in computational calculation.In addition,once the critical thickness of titanium layer is reached,graphene wrinkles are induced in composites because of Poisson's effect induced large lateral compression stress in the interface region.This study provides helpful insights into fundamental understanding reinforcing mechanism of graphene and ultimately contribute to the optimal design and performance of mechanically robust graphene-based metallic composites.
基金University Grants Commission (UGC)New Delhi for providing the research fund to carry out this work
文摘The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance methods. Inhibition efficiency （IE）, corrosion rate and surface coverage were evaluated at different concentrations of BBTS. The results of the investigation showed that this compound had good inhibiting properties for mild steel corrosion in hydrochloric acid and BBTS was a mixed-type inhibitor. BBTS chemisorbed at the electrode surface obeyed Langmuir adsorption isotherm and formed a stable surface complex on the mild steel surface. The synergistic effect of halide ion in acid solution suggested a co-adsorption of BBTS inhibitor by the adsorbed iodide ion.
基金financially supported by the National Key R&D Program of China(No.2021YFB3800602)the National Nature Science Foundation of China-NSAF(No.52172129)+1 种基金the Natural Science Foundation of Shaanxi Province(Nos.2021GXLH-Z-025 and 2020JM-004)Beilin 2021 Applied Technology Research and Development Project(No.GX2118)。
文摘BaTiO_(3)ceramics are difficult to withstand high electric fields,so the energy storage density is relatively low,inhabiting their applications for miniaturized and lightweight power electronic devices.To address this issue,we added Sr_(0.7)Bi_(0.2)TiO_(3)(SBT)into BaTiO_(3)(BT)to destroy the long-range ferroelectric domains.Ca^(2+)was introduced into BT-SBT in the form of CaTiO_(3)(CT),which has the effect of inhibiting the movement of A-site defects to reduce dielectric loss and refining the grains to increase the breakdown field strength.In addition,we have increased the density and grain uniformity of ceramics by repeated rolling of the green samples through the viscous polymer processing(VPP),to further increase the breakdown electric field.The BT-SBT-CT ceramics exhibit the high recoverable energy storage density of 4.0 J·cm^(-3)under electric field of 480 kV·cm^(-1).Its recoverable energy storage density varies by less than 8%in the temperature range of 30-150℃,indicating good temperature stability of the energy storage performance.In this work,the energy storage performance of barium titanate-based ceramics was greatly improved by transforming ferroelectrics into relaxor ferroelectrics and VPP method,which can bring new inspiration for the research of energy storage ceramics.
基金Sponsored by the Ministry of Science & Technology of China During the 11th Five-year Plan (Grant No. 2006BAJ05B07)
文摘Using powder-sintering method,SiO2-Al2O3-CaO-ZnO-R2O porous glass-ceramics were produced for analysis. Five samples with different SiO2 /CaO ratios were used in the research. The mechanical properties, microstructures and textures of porous glass-ceramics are investigated by using differential thermogravimetric analysis/differential thermal analysis ( TGA/SDTA) ,X-ray diffraction ( XRD) ,and scanning electron microsco- py ( SEM) . The activity energy of crystallization ( E) and crystallization kinetics parameter ( k) were calculated based on the modified JMA equation. The Avrami parameter n was obtained according to Augis-Bennett function. The results show that the k value of No. 1 sample ( SiO2 /CaO = 61∶ 18) is the largest among all samples, which tends to crystallize more easily,and crystallization processes of all samples are observed bulk crystallization. The main crystal phase observed is parawollastonite ( clinorhombic system) with puncheon shape. Poreforming agents decomposed at 100 - 500 ℃ form a large number of closed pores with micron dimension and several semi-open pores distribute uniformly in the glass-ceramics matrix. This work may be expected to be favorable for industrial scale applications of porous glass-ceramics in the field of building thermal insulation.
基金Turkish Scientific and Technological Research Council for the financial support of this work (Project No: 112T811)
文摘Zinc borate(ZB)particles dispersed in silicone oil(SO)at concentrations of φ=5vol%-20vol% were subjected to dielectric analysis to elucidate their polarization strength,time,and mechanism.Results revealed that all virgin dispersions lacked polarization.Triton X-100,a non-ionic surfactant,was added to ZB/SO dispersions to enhance the polarizability of ZB particles.The addition of 1vol% Triton X-100 enhanced the polarizability of ZB/SO dispersions,and the 15vol% ZB/SO system provided the highest dielectric difference Δε′(the difference in ε′values at zero and infinite frequency,Δε′=ε0–ε∝)of 3.64.The electrorheological(ER)activities of the ZB/SO/Triton-X dispersion system were determined through the ER response test,and viscoelastic behaviors were investigated via oscillation tests.A recoverable deformation of 36% under an applied electrical field strength of 1.5 kV/mm was detected through creep and creep recovery tests.
文摘In this work, the use of computational methods was essential to distinguish the three possible isomeric structures of the [RuCl3(H2O)2(Gly)] molecule. The characterization of these molecules was performed using IR, NMR and UV-VIS simulations. Some calculations related to the optimization of structures and properties such as chemical hardness and dipole moment were also conducted. The fac-cis isomer presented promising data when compared to the experimental data, indicating that this is the likely experimentally synthesized isomer. This study demonstrates the technical utility of the computational calculations by virtue of situations that prevent the realization of X-ray diffraction.
基金financially supported by Turkish Scientific and Technological Research Council(No.107 T 711)
文摘Electrorheological properties and creep-recovery behavior of polythiophene/polyoxymethylene-blend having PT（50%）/POM（50%） composition were investigated.Particle size,conductivity and dielectric values were measured to be 24.77μm,3.85×10^（-5） S·m^（-1） and 26.75,respectively.Sedimentation ratio was measured to be 64%at the end of 16 days.The effects of dispersed particle volume fraction,external electric field strength,shear rate,frequency and temperature on ER properties and storage modulus of PT/POM-blend/silicone oil（SO） suspensions were examined.Enhancement were observed in the electric field viscosities of the suspensions and thus they were classified as a smart material.Shear thinning non-Newtonian viscoelastic behavior was determined for PT/POM-blend/SO system.Further,time-dependent deformation was examined by creep-recovery tests and recoverable viscoelastic deformation established.
基金financially supported by the National Key Research Program of China(No.2021YFB3800602)the National Natural Science Foundation of China(Nos.52172238 and 51902264)。
文摘Film dielectric capacitors enabled with large breakdown field strength and high energy density play a key role for compact and integrated power systems.Nevertheless,the energy storage efficiency is always sacrificed as we tried to increase the energy density.This trade-off between energy density and efficiency means significant energy dissipation and thermal effects,which will lead to a deterioration ofthe reliability and lifetime of the dielectric capacitors.
文摘Castor oil is used to synthesize phenolic resin modified polyol. Castor oil, phenolic resin were taken in the molar ratio 0.07：0.027 and diethylene glycol （DEG） was also taken in varying hydroxyl numbers to achieve chemical modification in the backbone of synthesized polyol. Physico-chemical properties like acid value, OH value and moisture content of the modified polyol were measured. The prepared phenolic resin blended polyol were reacted with 4, 4-methylene diisocyanate and 2, 4-toluene diisocyanate to formulate the two component polyurethane （PU） coatings. Prepared coating is used to study properties such as gel time, surface dry, tack free and hard surface drying times. It was found that phenolic resin and diethyleneglycol used in synthesizing castor oil based modified polyols show the significant changes in physico-chemical properties of synthesized polyols. The variation in physico-chemical properties of synthesized polyol provide the information for desirable curing of polyurethane systems.
