The fused cast alumina-zirconia-silica(AZS)refractory is an indispensable material of the glass melting furnace,because of its outstanding corrosion resistance and low pollution to glass production.The exudation is on...The fused cast alumina-zirconia-silica(AZS)refractory is an indispensable material of the glass melting furnace,because of its outstanding corrosion resistance and low pollution to glass production.The exudation is one important index to evaluate the performance of fused cast AZS refractory products.In order to study the effects of chemical composition and microstructure on the exudation of fused cast AZS refractory materials,three types of fused-cast AZS refractory bricks(AZS33#,AZS36#and AZS41#)were selected from several companies as the research object,and their composition,bulk density,apparent porosity,the value of exudation,static corrosion rate and microstructure were discussed.The results show that the chemical composition,especially the content of SiO2 and Na2O,and the distribution of zirconia would greatly affect the content and viscosity of glass phase,thus affecting the glass exudation.This work will provide technical reference for the development of low exudation AZS refractories.展开更多
With the rapid development of the construction industry, all sectors of the society put forward higher requirements for the quality of construction projects. As a direct factor affecting the construction quality of co...With the rapid development of the construction industry, all sectors of the society put forward higher requirements for the quality of construction projects. As a direct factor affecting the construction quality of construction projects, building materials are usually sent to the testing institutions for testing before construction. If there is no accurate testing results, it will affect the performance of construction materials, waste construction costs, and even harm the safety and quality of construction projects. This paper analyzes the problems existing in the quality inspection of building materials in detail, and puts forward some effective strategies for reference.展开更多
The high-cycle fatigue fracture characteristics and damage mechanism of nickel-based single crystal superalloys at 850℃ was investigated.The results indicate that high-cycle fatigue cracks in single crystal superallo...The high-cycle fatigue fracture characteristics and damage mechanism of nickel-based single crystal superalloys at 850℃ was investigated.The results indicate that high-cycle fatigue cracks in single crystal superalloys generally originate from defect locations on the subsurface or interior of the specimen at 850℃.Under the condition of stress ratio R=0.05,as the fatigue load decreases,the high-cycle fatigue life gradually increases.The high-cycle fatigue fracture is mainly characterized by octahedral slip mechanism.At high stress and low lifespan,the fracture exhibits single or multiple slip surface features.Some fractures originate along a vertical small plane and then propagate along the{111}slip surface.At low stress and high lifespan,the fracture surface tend to alternate and expand along multiple slip planes after originating from subsurface or internal sources,exhibiting characteristics of multiple slip planes.Through electron backscatter diffraction and transmission electron microscope analysis,there is obvious oxidation behavior on the surface of the high-cycle fatigue fracture,and the fracture section is composed of oxidation layer,distortion layer,and matrix layer from the outside to the inside.Among them,the main components of the oxidation layer are oxides of Ni and Co.The distortion layer is mainly distributed in the form of elongated or short rod-shaped oxides of Al,Ta,and W.The matrix layer is a single crystal layer.Crack initiation and propagation mechanism were obtained by systematical analysis of a large number of highcycle fatigue fractures.In addition,the stress ratio of 0.05 is closer to the vibration mode of turbine blades during actual service,providing effective guidance for the study of failure and fracture mechanisms of turbine blades.展开更多
Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis so...Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis software was used for quantitative analysis.The variation of mechanical properties before and after overtemperature treatment was tested.Results show that the Ti_(2)AlNb alloy consists of B2 phase and lamellar O phase before and after overtemperature treatment.After overtemperature treatment,partial B2 phase is transformed into the O phase,and the lamellar structure of O phase suffers discontinuous coarsening and spherolization.The coarsening degree is increased with the increase in temperature and prolongation of treatment time,and O phase content is also gradually increased.The microhardness and tensile properties of Ti_(2)AlNb alloys at room and high temperatures are decreased with the increase in temperature and prolongation of treatment time,and the high-temperature tensile strength exhibits relatively larger decrement.An obvious linear relationship exists between microhardness and O phase content.Both the microhardness and the O phase content are important parameters to evaluate the overtemperature service damage degree of precision-cast Ti_(2)AlNb alloy.展开更多
This research study fabrics to ensure that they are free from carcinogenic dyes. It has been observed that there are poor-quality fabrics and consumers go to buy them without paying attention to the risks of using pro...This research study fabrics to ensure that they are free from carcinogenic dyes. It has been observed that there are poor-quality fabrics and consumers go to buy them without paying attention to the risks of using prohibited materials in the manufacture of these fabrics, and the use of unknown dyes has proven that some of them cause diseases to humans, especially children, that cause cancerous diseases. With the study sample consisting of (7), the study results indicate the presence of toxic formaldehyde in all sample dyes obtained from discount markets and online shopping.展开更多
Perovskite/Si tandem solar cells(TSCs)present great potential to surpass the Shockley-Queisser limit of single-junction solar cells for further advancing the power conversion efficiency(PCE)of solar cells.However,the ...Perovskite/Si tandem solar cells(TSCs)present great potential to surpass the Shockley-Queisser limit of single-junction solar cells for further advancing the power conversion efficiency(PCE)of solar cells.However,the fabrication of TSCs usually encounters challenge of selecting suitable sputtering buffer layer(SBL)to prevent the bombardment during the transparent electrode deposition.Herein,we introduce an indium oxide(In_(2)O_(3))buffer layer via e-beam deposition to fabricate semi-transparent perovskite solar cells(ST-PSCs).The optical transmittance and electrical conductivity of In_(2)O_(3)highly depend on the deposition rate.High deposition rate results in high ratio of metallic indium in the film,which causes severe parasitic absorption.A 20 nm-thick In_(2)O_(3)film deposited at lower rate demonstrated high conductivity,transmittance and robust protection during sputtering.A 1.68 eV ST-PSC incorporating this In_(2)O_(3)buffer layer exhibits a champion PCE of 20.20%,demonstrating the excellent optoelectronic and protective properties of In_(2)O_(3).When combined with a Si subcell,the 4-terminal TSC obtains a remarkable PCE of 30.04%,Importantly,the unencapsulated ST-PSC maintained 80%of initial PCE after 423 h of continuous light soaking in N_(2).This work has provided a facile and instrumental transparent SBL strategy for perovskite/Si TSCs.展开更多
Large-scale deep-seated landslides pose a significant threat to human life and infrastructure.Therefore,closely monitoring these landslides is crucial for assessing and mitigating their associated risks.In this paper,...Large-scale deep-seated landslides pose a significant threat to human life and infrastructure.Therefore,closely monitoring these landslides is crucial for assessing and mitigating their associated risks.In this paper,the authors introduce the So Lo Mon framework,a comprehensive monitoring system developed for three large-scale landslides in the Autonomous Province of Bolzano,Italy.A web-based platform integrates various monitoring data(GNSS,topographic data,in-place inclinometer),providing a user-friendly interface for visualizing and analyzing the collected data.This facilitates the identification of trends and patterns in landslide behaviour,enabling the triggering of warnings and the implementation of appropriate mitigation measures.The So Lo Mon platform has proven to be an invaluable tool for managing the risks associated with large-scale landslides through non-structural measures and driving countermeasure works design.It serves as a centralized data repository,offering visualization and analysis tools.This information empowers decisionmakers to make informed choices regarding risk mitigation,ultimately ensuring the safety of communities and infrastructures.展开更多
Numerous defects at the buried interface of perovskite film and the exacerbated oxidation and degradation of tin-lead(Sn-Pb)perovskites induced by poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS),du...Numerous defects at the buried interface of perovskite film and the exacerbated oxidation and degradation of tin-lead(Sn-Pb)perovskites induced by poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS),due to its hygroscopic and acidic nature,limit performance improvement of SnPb perovskite solar cells(PSCs).To address these issues,1-Ethyl-3-Guanidinothiourea-Hydrochloride(EGH)was employed as a multifunctional modifier at the PEDOT:PSS/perovskite interface to regulate the buried interface behaviors of Sn-Pb PSCs.EGH can not only passivate the defects of the perovskite buried interface and regulate the work function of PEDOT:PSS for a more matched interface energy level,but also prevent the perovskite film from erosion damage by the acidic PEDOT:PSS for a more stable PEDOT:PSS/perovskite interface.Moreover,the interfacial charge transport dynamics were significantly improved by obviously suppressing interfacial non-radiative recombination losses.As a consequence,EGH-tailored 1.25 eV Sn-Pb PSCs yielded a champion PCE of 23.20%,featuring enhanced long-term stability.展开更多
The fabrication of efficient and stable flexible perovskite solar modules(F-PSMs)using poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA)remains a significant challenge due to its hydrophobic properties and the mis...The fabrication of efficient and stable flexible perovskite solar modules(F-PSMs)using poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA)remains a significant challenge due to its hydrophobic properties and the mismatch in interface energy-level alignment.Here,we introduced[2-(3,6-dimethoxy-9H-carba zol-9-yl)ethyl]phosphonic acid(MeO-2PACz)to modify the PTAA layer,which effectively suppressed surface potential fluctuations and aligned energy levels at the interface of PTAA/perovskite.Additionally,MeO-2PACz enhanced the hydrophilicity of PTAA,facilitating the fabrication of dense,uniform,and pinhole-free perovskite films on large-area flexible substrates.As a result,we achieved an F-PSM with a power conversion efficiency(PCE)of 16.6% and an aperture area of 64 cm^(2),which is the highest reported value among F-PSMs with an active area exceeding 35 cm^(2)based on PTAA.Moreover,the encapsulated module demonstrated outstanding long-term operational stability,retaining 90.2% of its initial efficiency after 1000 bending cycles(5 mm radius),87.2% after 1000 h of continuous illumination,and 80.3% under combined thermal and humid conditions(85℃ and 85% relative humidity),representing one of the most stable F-PSMs reported to date.展开更多
The efficiencies of free and immobilized bacterial cultures of petroleum hydrocarbon degraders were evaluated and compared in this study. Hydrocarbon-degrading microbial communities with high tolerance to and high deg...The efficiencies of free and immobilized bacterial cultures of petroleum hydrocarbon degraders were evaluated and compared in this study. Hydrocarbon-degrading microbial communities with high tolerance to and high degrading ability of crude oil were obtained from the soil contaminated with crude oil in the Yellow River Delta. Then, the microbial cells were immobilized in sodium alginate （SA） beads and sodium Mginate-diatomite （SAD） beads. The biodegradation of crude oil in soil by immobilized cells was compared with that by free cells at three inoculation concentrations, 1× 104 colony forming units （cfu） kg-^（-1）（low concentration, L）, 5 × 104 cfu kg^（-1） （medium concentration, M）, and 1× 105 cfu kg^（-1） （high concentration, H）. At 20 d after inoculation, the maximum degradation rate in the immobilized systems reached 29.8% （SAD-M）, significantly higher （P 〈 0.05） than that of the free cells （21.1%）, and the SAD beads showed greater degradation than the SA beads. Moreover, both microbial populations and total microbial activity reached significantly higher level （P 〈 0.05） in the immobilized systems than free cell systems at a same initial inoculation amount. The scanning electronic microscope （SEM） images also confirmed the advantages of the immobilized microstructure of SAD beads. The enhanced degradation and bacterial growth in the SAD beads indicated the high potential of SAD beads as an effective option for bioremediation of crude oil-contaminated soils in the Yellow River Delta.展开更多
The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 an...The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 and 190 mm/min, providing R/v ratio between 5.00 and 10.27. The welded joints were tested by means of both non-destructive （visual, penetrant and X-ray inspection） and destructive （metallographic, tension and hardness） testing. In all specimens typical zones are revealed, with corresponding differences in grain size. Tensile efficiency of the joints obtained is in the range of 52.2%to 82.3%. The results show that the best quality is obtained at R/v ratio of 8.06, 10.17 and 10.27. This behavior is attributed to the assumption that the material flows around the pin with an optimal speed, i.e. sufficient amount of material is available to fill the gap and prevent tunnel formation. R/v ratio also showed influence on hardness distribution, onion features and crack initiation/propagation zones.展开更多
The effects of T4,T5,and T6 treatment on the microstructure and mechanical properties of the extruded Mg-4.3Gd-3.2Y-1.2Zn-0.5Zr(wt.%)alloy with a relatively low RE content(7.5 wt.%)were investigated.T4 treatment at 45...The effects of T4,T5,and T6 treatment on the microstructure and mechanical properties of the extruded Mg-4.3Gd-3.2Y-1.2Zn-0.5Zr(wt.%)alloy with a relatively low RE content(7.5 wt.%)were investigated.T4 treatment at 450–500°C induces a gradual grain growth ofα-Mg but an obvious transition of texture component from<0001>⊥ED to<0001>∥ED.Interdendritic LPSO phases are highly stable against annealing while intragranular ones experience dissolution and re-precipitation.After peak-ageing at 200°C,the elongation of as-extruded and T4 samples is just slightly reduced or even increased due to the weak ageing hardening response.T5 sample exhibits an attractive combination of strength and ductility,with a tensile yield strength(TYS)of 303 MPa and elongation of 20.0%.The Hall–Petch relation for the alloys with or without ageing treatment has been estimated.Grain boundary strengthening rather than precipitation strengthening has the dominant contribution to TYS,and a modified equation is developed to predict grain boundary strengthening values for Mg-Gd-Y-Zn-Zr alloys which contain different Schmid factors for basal slip.展开更多
For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching proces...For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching processes of AISI P20 steel block such as oil quenching, direct water quenching, water quenching with precooling and water quenching with pre-cooling and self-tempering were numerically investigated by computer simulation based on the detailed discussion on the mathematical models of quenching processes including partial differential equations of heat transfer, thermal physical properties, latent heat, heat transfer coefficient and calculation of phase transformation, The results show that the water quenching with pre-cooling and self-tempering process can not only effectively avoid quenching cracks, but also obtain deeper harden depth than oil quenching.展开更多
The mechanical behaviour of a quasi-brittle material,i.e.Pietra Serena sandstone,was investigated both numerically and experimentally in order to build a reliable numerical modelling system applicable to more complex ...The mechanical behaviour of a quasi-brittle material,i.e.Pietra Serena sandstone,was investigated both numerically and experimentally in order to build a reliable numerical modelling system applicable to more complex cases.The Karagozian and Case concrete(KCC)model was exploited as the material constitutive law and a new method to utilise this model for efficient and accurate simulation of quasibrittle materials is discussed.The capability of this model is evaluated by comparing the results of the numerical simulations with the corresponding experimental results,and the method itself is critically assessed.展开更多
Vibration fatigue is the main failure mode of compressor blade. Evaluating the vibration stress of blade that leads to cracking is very useful for analysis of vibration fatigue. In this paper, fatigue stress estimatio...Vibration fatigue is the main failure mode of compressor blade. Evaluating the vibration stress of blade that leads to cracking is very useful for analysis of vibration fatigue. In this paper, fatigue stress estimation methods by quantitative fractography were studied through experimental blade and in-service first-stage compressor blade in order to evaluate the initiation vibration stress of in-service blade. The analysis process of initiation vibration stress was established. The evaluating result of vibration stress of in-service blade subjected to centrifugal force and bending vibration stress agrees with aero engine test result. It is shown that the evaluation method can not only evaluate the equivalent fatigue stresses of different crack depths but also yield the initiation equivalent fatigue stress.展开更多
Two Mo5SiB2 (T2)-based alloys with nominal compositions of Mo-12.5Si-25B and Mo-14Si-28B (molar fraction, %) were prepared in an arc-melting furnace, and their oxidation kinetics from 1 000 to 1 300 ℃ were studied. T...Two Mo5SiB2 (T2)-based alloys with nominal compositions of Mo-12.5Si-25B and Mo-14Si-28B (molar fraction, %) were prepared in an arc-melting furnace, and their oxidation kinetics from 1 000 to 1 300 ℃ were studied. The microstructures of the alloys were characterized by X-ray diffractometry(XRD) and scanning electron microscopy(SEM) with energy dispersive spectroscopy (EDS). The oxide scales of both alloys oxidized at 1 200 ℃ for 10 min, 2 h and 100 h were investigated by surface XRD and cross-sectional SEM-EDS. The results show that the matrix of both alloys consists of T2. The dispersions of Mo-12.5Si-25B alloy are Mo and Mo3Si, and the dispersions of Mo-14Si-28B alloy are Mo5Si3 (T1) and MoB. The cyclic oxidation kinetics data exhibit initial rapid mass loss followed by slow mass loss. The mass loss of Mo-12.5Si-25B alloy is much faster than that of Mo-14Si-28B alloy at 1 200 and 1 300 ℃. For 10 min exposure, both alloys form irregular and porous thin scale. For 2 h exposure, Mo-12.5Si-25B alloy forms irregular thin scale and the scale contains large cracks, and Mo-14Si-28B alloy forms sound and continuous scale. For 100 h exposure, Mo-12.5Si-25B and Mo-14Si-28B alloys form sound and continuous scale about 50-75 μm and 40-45 μm in thickness, respectively. The better oxidation resistance of Mo-14Si-28B alloy is due to a sound and continuous B-SiO2 layer formation in the early stage of oxidation.展开更多
In the marine environment,the protective coatings face serious corrosion and biofouling problem,lim-itations,and challenges that made self-healing coatings unable to perform both anti-corrosion and anti-biofouling dua...In the marine environment,the protective coatings face serious corrosion and biofouling problem,lim-itations,and challenges that made self-healing coatings unable to perform both anti-corrosion and anti-biofouling dual-function at the same time.Here we constructed the corrosion resistance and anti-biofouling self-healing coating by integrating nano-containers into the coating matrix,the 2-Undecylimidazoline(ULM)acted as a corrosion inhibitor and anti-biofouling dual-functional agent which was loaded on the natural container attapulgite(ATP).To obtain high healing efficiency,a fluidity-driven self-healing silicone oil coating was thickened by fibrous ATP to enhance its stability,which played a key role in the self-healing and long-term corrosion resistance.The self-healing time of ULM@ATP rein-forced oil coating was 4 s at least in the air and up to 30 s in the 1 M HCl solution.Meanwhile,the ULM@ATP can significantly enhance the corrosion resistance of the self-healing coating,with the best effect achieved when the content of ULM@ATP was 5 wt.%.The impedance modulus of ULM@ATP-2 still reached 1.62×10^(8)Ωcm^(2) after 480 immersion in 3.5 wt.%NaCl solution,which is 3 orders of magnitude high than pure Oil coating(2.17×10^(5)Ωcm^(2)).The restructure of the ATP network and the release of ULM could largely inhibit the corrosion of metal.The continuous open circuit potential of the compos-ite coating performed the potentially infinite self-healing capacity.The self-healing performances of the composite coating in strong acid and base solutions exhibited high environmental suitability.This anti-corrosion and anti-biofouling(the surface coverage of adhered chlorella decreased 96.88%)dual-function strategy of self-healing coatings could be also realized by many other porous nano-materials or function modifications.The self-healing performances of the composite coating in strong acid and base solutions exhibited high environmental suitability.This anti-corrosion and anti-biofouling dual-function strategy of self-healing coatings could be also realized by many other porous nano-materials or function modifica-tions.The rapid response self-healing coating possessed anti-biofouling and active self-healing functions and showed wide application under more service environments.展开更多
The study focused on investigating the effect of Deep Cryogenic Treatment(DCT)on the mechanical and ballistic properties of AA7075-T6 aluminum alloy.The microstructure,microhardness,tensile strength,and impact strengt...The study focused on investigating the effect of Deep Cryogenic Treatment(DCT)on the mechanical and ballistic properties of AA7075-T6 aluminum alloy.The microstructure,microhardness,tensile strength,and impact strength of the Base Material(BM)and DCT-treated 7075 samples were analyzed through metallographic analysis and mechanical tests.The microstructure of the DCT-treated 7075 samples revealed fine grains and a distribution of secondary phase particles.The tensile strength,impact strength,and microhardness of DCT-treated samples increased by 7.41%,4%,and 9.68%,respectively,compared to the BM samples.The fractography analysis of the tensile samples showed cleavage facets,microvoids,and dimples in both the samples.The ballistic behavior of the BM and DCT target plates were studied by impacting hard steel core projectiles at a velocity of 750±10 m/s.The target plates failed due to petaling and ductile hole enlargement,and the depth of penetration(DOP)of the DCT target was less than that of the BM target,indicating a higher ballistic resistance.The post-ballistic microstructure examination of the target plates showed the formation of an Adiabatic Shear Band(ASB)without any cracks.It was concluded that the DCT treatment improved the mechanical and ballistic properties of the aluminum alloy due to grain refinement and high dislocation density.展开更多
Creep experiments of the TiAl alloy with high Nb content were conducted to consider both the temperature dependence and stress dependence of its creep behavior.The creep curves were characterized by Theta constitutive...Creep experiments of the TiAl alloy with high Nb content were conducted to consider both the temperature dependence and stress dependence of its creep behavior.The creep curves were characterized by Theta constitutive model,and Newton-Gauss method was applied to obtain the material parameters.Based on the rupture strain,the rupture life of the TiAl alloy was able to be predicted by Theta constitutive model.The results show that the creep curves of the TiAl alloy contain primary creep,secondary creep and tertiary creep stages,especially for the lower stress.The rupture life of the TiAl alloy decreases with the increase in either applied stress or temperature.Theta constitutive model is able to describe the creep deformation of the TiAl alloy accurately,and the predicted life agrees well with the experimental result.展开更多
The Hot deformation and martensitic transformation behaviors of Fe-32%Ni alloy was investigated by measurements of electrical resistance and X-ray diffraction. With the increase in strain, the austenite goes through f...The Hot deformation and martensitic transformation behaviors of Fe-32%Ni alloy was investigated by measurements of electrical resistance and X-ray diffraction. With the increase in strain, the austenite goes through from the work-hardened to the partial dynamcally re-crystallized and then to the completed dynamically re-crystallized. The martensitic transformation characteristics depend on the austenite states. The work-hardening in small strain is helpful to martensitic transformation due to the low dislocation density and little lattice distortion, while the high dislocation density and severe lattice distortion by the increase in strain will hinder the martensitic nucleation. Once dynamic re-crystallization （ DRX ） takes place, the martensitic transformation will be enhanced again, which is related to the heterogeneous dynamic substructures. The growing DRX grain can enhance the martensitic nucleation due to the low dislocation density near its grain boundary.展开更多
文摘The fused cast alumina-zirconia-silica(AZS)refractory is an indispensable material of the glass melting furnace,because of its outstanding corrosion resistance and low pollution to glass production.The exudation is one important index to evaluate the performance of fused cast AZS refractory products.In order to study the effects of chemical composition and microstructure on the exudation of fused cast AZS refractory materials,three types of fused-cast AZS refractory bricks(AZS33#,AZS36#and AZS41#)were selected from several companies as the research object,and their composition,bulk density,apparent porosity,the value of exudation,static corrosion rate and microstructure were discussed.The results show that the chemical composition,especially the content of SiO2 and Na2O,and the distribution of zirconia would greatly affect the content and viscosity of glass phase,thus affecting the glass exudation.This work will provide technical reference for the development of low exudation AZS refractories.
文摘With the rapid development of the construction industry, all sectors of the society put forward higher requirements for the quality of construction projects. As a direct factor affecting the construction quality of construction projects, building materials are usually sent to the testing institutions for testing before construction. If there is no accurate testing results, it will affect the performance of construction materials, waste construction costs, and even harm the safety and quality of construction projects. This paper analyzes the problems existing in the quality inspection of building materials in detail, and puts forward some effective strategies for reference.
基金National Science and Technology Major Project(J2019-VI-0022-0138)。
文摘The high-cycle fatigue fracture characteristics and damage mechanism of nickel-based single crystal superalloys at 850℃ was investigated.The results indicate that high-cycle fatigue cracks in single crystal superalloys generally originate from defect locations on the subsurface or interior of the specimen at 850℃.Under the condition of stress ratio R=0.05,as the fatigue load decreases,the high-cycle fatigue life gradually increases.The high-cycle fatigue fracture is mainly characterized by octahedral slip mechanism.At high stress and low lifespan,the fracture exhibits single or multiple slip surface features.Some fractures originate along a vertical small plane and then propagate along the{111}slip surface.At low stress and high lifespan,the fracture surface tend to alternate and expand along multiple slip planes after originating from subsurface or internal sources,exhibiting characteristics of multiple slip planes.Through electron backscatter diffraction and transmission electron microscope analysis,there is obvious oxidation behavior on the surface of the high-cycle fatigue fracture,and the fracture section is composed of oxidation layer,distortion layer,and matrix layer from the outside to the inside.Among them,the main components of the oxidation layer are oxides of Ni and Co.The distortion layer is mainly distributed in the form of elongated or short rod-shaped oxides of Al,Ta,and W.The matrix layer is a single crystal layer.Crack initiation and propagation mechanism were obtained by systematical analysis of a large number of highcycle fatigue fractures.In addition,the stress ratio of 0.05 is closer to the vibration mode of turbine blades during actual service,providing effective guidance for the study of failure and fracture mechanisms of turbine blades.
文摘Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis software was used for quantitative analysis.The variation of mechanical properties before and after overtemperature treatment was tested.Results show that the Ti_(2)AlNb alloy consists of B2 phase and lamellar O phase before and after overtemperature treatment.After overtemperature treatment,partial B2 phase is transformed into the O phase,and the lamellar structure of O phase suffers discontinuous coarsening and spherolization.The coarsening degree is increased with the increase in temperature and prolongation of treatment time,and O phase content is also gradually increased.The microhardness and tensile properties of Ti_(2)AlNb alloys at room and high temperatures are decreased with the increase in temperature and prolongation of treatment time,and the high-temperature tensile strength exhibits relatively larger decrement.An obvious linear relationship exists between microhardness and O phase content.Both the microhardness and the O phase content are important parameters to evaluate the overtemperature service damage degree of precision-cast Ti_(2)AlNb alloy.
文摘This research study fabrics to ensure that they are free from carcinogenic dyes. It has been observed that there are poor-quality fabrics and consumers go to buy them without paying attention to the risks of using prohibited materials in the manufacture of these fabrics, and the use of unknown dyes has proven that some of them cause diseases to humans, especially children, that cause cancerous diseases. With the study sample consisting of (7), the study results indicate the presence of toxic formaldehyde in all sample dyes obtained from discount markets and online shopping.
基金supported by National Natural Science Foundation of China(Grant Nos.52102304 and 52172238)Open Project of Shaanxi Laboratory of Aerospace Power(Grant No.2021SXSYS01-03)+1 种基金Shaanxi Bureau of Science and Technology(Award No.2022KWZ-07)the Fundamental Research Funds for the Central Universities(Grant No.3102019JC0005)。
文摘Perovskite/Si tandem solar cells(TSCs)present great potential to surpass the Shockley-Queisser limit of single-junction solar cells for further advancing the power conversion efficiency(PCE)of solar cells.However,the fabrication of TSCs usually encounters challenge of selecting suitable sputtering buffer layer(SBL)to prevent the bombardment during the transparent electrode deposition.Herein,we introduce an indium oxide(In_(2)O_(3))buffer layer via e-beam deposition to fabricate semi-transparent perovskite solar cells(ST-PSCs).The optical transmittance and electrical conductivity of In_(2)O_(3)highly depend on the deposition rate.High deposition rate results in high ratio of metallic indium in the film,which causes severe parasitic absorption.A 20 nm-thick In_(2)O_(3)film deposited at lower rate demonstrated high conductivity,transmittance and robust protection during sputtering.A 1.68 eV ST-PSC incorporating this In_(2)O_(3)buffer layer exhibits a champion PCE of 20.20%,demonstrating the excellent optoelectronic and protective properties of In_(2)O_(3).When combined with a Si subcell,the 4-terminal TSC obtains a remarkable PCE of 30.04%,Importantly,the unencapsulated ST-PSC maintained 80%of initial PCE after 423 h of continuous light soaking in N_(2).This work has provided a facile and instrumental transparent SBL strategy for perovskite/Si TSCs.
基金funded by the So Lo Mon project“Monitoraggio a Lungo Termine di Grandi Frane basato su Sistemi Integrati di Sensori e Reti”(Longterm monitoring of large-scale landslides based on integrated systems of sensors and networks),Program EFRE-FESR 2014–2020,Project EFRE-FESR4008 South Tyrol–Person in charge:V.Mair。
文摘Large-scale deep-seated landslides pose a significant threat to human life and infrastructure.Therefore,closely monitoring these landslides is crucial for assessing and mitigating their associated risks.In this paper,the authors introduce the So Lo Mon framework,a comprehensive monitoring system developed for three large-scale landslides in the Autonomous Province of Bolzano,Italy.A web-based platform integrates various monitoring data(GNSS,topographic data,in-place inclinometer),providing a user-friendly interface for visualizing and analyzing the collected data.This facilitates the identification of trends and patterns in landslide behaviour,enabling the triggering of warnings and the implementation of appropriate mitigation measures.The So Lo Mon platform has proven to be an invaluable tool for managing the risks associated with large-scale landslides through non-structural measures and driving countermeasure works design.It serves as a centralized data repository,offering visualization and analysis tools.This information empowers decisionmakers to make informed choices regarding risk mitigation,ultimately ensuring the safety of communities and infrastructures.
基金financially supported by the National Key R&D Program of China(2022YFB4200303 to D.Zhao)the National Natural Science Foundation of China(62174112,52461160298 to D.Zhao and E30853YM19 to C.Xiao)+2 种基金the Natural Science Foundation of Sichuan Province(2024NSFSC1011 to C.Chen)the Fundamental Research Funds for the Central Universities(YJ2021157 to C.Chen)the Engineering Featured Team Fund of Sichuan University(2020SCUNG102 to D.Zhao)。
文摘Numerous defects at the buried interface of perovskite film and the exacerbated oxidation and degradation of tin-lead(Sn-Pb)perovskites induced by poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS),due to its hygroscopic and acidic nature,limit performance improvement of SnPb perovskite solar cells(PSCs).To address these issues,1-Ethyl-3-Guanidinothiourea-Hydrochloride(EGH)was employed as a multifunctional modifier at the PEDOT:PSS/perovskite interface to regulate the buried interface behaviors of Sn-Pb PSCs.EGH can not only passivate the defects of the perovskite buried interface and regulate the work function of PEDOT:PSS for a more matched interface energy level,but also prevent the perovskite film from erosion damage by the acidic PEDOT:PSS for a more stable PEDOT:PSS/perovskite interface.Moreover,the interfacial charge transport dynamics were significantly improved by obviously suppressing interfacial non-radiative recombination losses.As a consequence,EGH-tailored 1.25 eV Sn-Pb PSCs yielded a champion PCE of 23.20%,featuring enhanced long-term stability.
基金financially supported by the Key Fund of Tianjin Natural Science Foundation,China Project of Tianjin Natural Science Foundation(24JCZDJC00510)the National Natural Science Foundation of China,China(22475147)the Fundamental Research Funds for the Central Universities,China。
文摘The fabrication of efficient and stable flexible perovskite solar modules(F-PSMs)using poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA)remains a significant challenge due to its hydrophobic properties and the mismatch in interface energy-level alignment.Here,we introduced[2-(3,6-dimethoxy-9H-carba zol-9-yl)ethyl]phosphonic acid(MeO-2PACz)to modify the PTAA layer,which effectively suppressed surface potential fluctuations and aligned energy levels at the interface of PTAA/perovskite.Additionally,MeO-2PACz enhanced the hydrophilicity of PTAA,facilitating the fabrication of dense,uniform,and pinhole-free perovskite films on large-area flexible substrates.As a result,we achieved an F-PSM with a power conversion efficiency(PCE)of 16.6% and an aperture area of 64 cm^(2),which is the highest reported value among F-PSMs with an active area exceeding 35 cm^(2)based on PTAA.Moreover,the encapsulated module demonstrated outstanding long-term operational stability,retaining 90.2% of its initial efficiency after 1000 bending cycles(5 mm radius),87.2% after 1000 h of continuous illumination,and 80.3% under combined thermal and humid conditions(85℃ and 85% relative humidity),representing one of the most stable F-PSMs reported to date.
基金the National Natural Science Foundation of China (No.41073067)the Key Program of the Ministry of Education,China (No.308016)the National Major Special Technological Programme Concerning Water Pollution Control and Management of China (No.2009ZX07010-008)
文摘The efficiencies of free and immobilized bacterial cultures of petroleum hydrocarbon degraders were evaluated and compared in this study. Hydrocarbon-degrading microbial communities with high tolerance to and high degrading ability of crude oil were obtained from the soil contaminated with crude oil in the Yellow River Delta. Then, the microbial cells were immobilized in sodium alginate （SA） beads and sodium Mginate-diatomite （SAD） beads. The biodegradation of crude oil in soil by immobilized cells was compared with that by free cells at three inoculation concentrations, 1× 104 colony forming units （cfu） kg-^（-1）（low concentration, L）, 5 × 104 cfu kg^（-1） （medium concentration, M）, and 1× 105 cfu kg^（-1） （high concentration, H）. At 20 d after inoculation, the maximum degradation rate in the immobilized systems reached 29.8% （SAD-M）, significantly higher （P 〈 0.05） than that of the free cells （21.1%）, and the SAD beads showed greater degradation than the SA beads. Moreover, both microbial populations and total microbial activity reached significantly higher level （P 〈 0.05） in the immobilized systems than free cell systems at a same initial inoculation amount. The scanning electronic microscope （SEM） images also confirmed the advantages of the immobilized microstructure of SAD beads. The enhanced degradation and bacterial growth in the SAD beads indicated the high potential of SAD beads as an effective option for bioremediation of crude oil-contaminated soils in the Yellow River Delta.
基金Ministry of Education and Science of Serbia for financial support through Project TR34018
文摘The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 and 190 mm/min, providing R/v ratio between 5.00 and 10.27. The welded joints were tested by means of both non-destructive （visual, penetrant and X-ray inspection） and destructive （metallographic, tension and hardness） testing. In all specimens typical zones are revealed, with corresponding differences in grain size. Tensile efficiency of the joints obtained is in the range of 52.2%to 82.3%. The results show that the best quality is obtained at R/v ratio of 8.06, 10.17 and 10.27. This behavior is attributed to the assumption that the material flows around the pin with an optimal speed, i.e. sufficient amount of material is available to fill the gap and prevent tunnel formation. R/v ratio also showed influence on hardness distribution, onion features and crack initiation/propagation zones.
基金the National Natural Science Foundation of China(Nos.51904036 and 51874049)the Hunan Provincial Natural Science Foundation of China(Nos.2020JJ5600 and 2018JJ2365)+1 种基金the Hunan Education Department Outstanding Youth Project of China(No.17B069)the Scientific Research Project of Hunan Education Department(No.20C0088).
文摘The effects of T4,T5,and T6 treatment on the microstructure and mechanical properties of the extruded Mg-4.3Gd-3.2Y-1.2Zn-0.5Zr(wt.%)alloy with a relatively low RE content(7.5 wt.%)were investigated.T4 treatment at 450–500°C induces a gradual grain growth ofα-Mg but an obvious transition of texture component from<0001>⊥ED to<0001>∥ED.Interdendritic LPSO phases are highly stable against annealing while intragranular ones experience dissolution and re-precipitation.After peak-ageing at 200°C,the elongation of as-extruded and T4 samples is just slightly reduced or even increased due to the weak ageing hardening response.T5 sample exhibits an attractive combination of strength and ductility,with a tensile yield strength(TYS)of 303 MPa and elongation of 20.0%.The Hall–Petch relation for the alloys with or without ageing treatment has been estimated.Grain boundary strengthening rather than precipitation strengthening has the dominant contribution to TYS,and a modified equation is developed to predict grain boundary strengthening values for Mg-Gd-Y-Zn-Zr alloys which contain different Schmid factors for basal slip.
文摘For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching processes of AISI P20 steel block such as oil quenching, direct water quenching, water quenching with precooling and water quenching with pre-cooling and self-tempering were numerically investigated by computer simulation based on the detailed discussion on the mathematical models of quenching processes including partial differential equations of heat transfer, thermal physical properties, latent heat, heat transfer coefficient and calculation of phase transformation, The results show that the water quenching with pre-cooling and self-tempering process can not only effectively avoid quenching cracks, but also obtain deeper harden depth than oil quenching.
文摘The mechanical behaviour of a quasi-brittle material,i.e.Pietra Serena sandstone,was investigated both numerically and experimentally in order to build a reliable numerical modelling system applicable to more complex cases.The Karagozian and Case concrete(KCC)model was exploited as the material constitutive law and a new method to utilise this model for efficient and accurate simulation of quasibrittle materials is discussed.The capability of this model is evaluated by comparing the results of the numerical simulations with the corresponding experimental results,and the method itself is critically assessed.
基金financially supported by Equipment Advance Research Fund of China (No. 9140A1211HK51)
文摘Vibration fatigue is the main failure mode of compressor blade. Evaluating the vibration stress of blade that leads to cracking is very useful for analysis of vibration fatigue. In this paper, fatigue stress estimation methods by quantitative fractography were studied through experimental blade and in-service first-stage compressor blade in order to evaluate the initiation vibration stress of in-service blade. The analysis process of initiation vibration stress was established. The evaluating result of vibration stress of in-service blade subjected to centrifugal force and bending vibration stress agrees with aero engine test result. It is shown that the evaluation method can not only evaluate the equivalent fatigue stresses of different crack depths but also yield the initiation equivalent fatigue stress.
基金Project(2003AA305750) supported by the National High Technology Research and Development Program of ChinaProject (NCET- 04-0386) supported by the New Century Excellent Talents in University, China
文摘Two Mo5SiB2 (T2)-based alloys with nominal compositions of Mo-12.5Si-25B and Mo-14Si-28B (molar fraction, %) were prepared in an arc-melting furnace, and their oxidation kinetics from 1 000 to 1 300 ℃ were studied. The microstructures of the alloys were characterized by X-ray diffractometry(XRD) and scanning electron microscopy(SEM) with energy dispersive spectroscopy (EDS). The oxide scales of both alloys oxidized at 1 200 ℃ for 10 min, 2 h and 100 h were investigated by surface XRD and cross-sectional SEM-EDS. The results show that the matrix of both alloys consists of T2. The dispersions of Mo-12.5Si-25B alloy are Mo and Mo3Si, and the dispersions of Mo-14Si-28B alloy are Mo5Si3 (T1) and MoB. The cyclic oxidation kinetics data exhibit initial rapid mass loss followed by slow mass loss. The mass loss of Mo-12.5Si-25B alloy is much faster than that of Mo-14Si-28B alloy at 1 200 and 1 300 ℃. For 10 min exposure, both alloys form irregular and porous thin scale. For 2 h exposure, Mo-12.5Si-25B alloy forms irregular thin scale and the scale contains large cracks, and Mo-14Si-28B alloy forms sound and continuous scale. For 100 h exposure, Mo-12.5Si-25B and Mo-14Si-28B alloys form sound and continuous scale about 50-75 μm and 40-45 μm in thickness, respectively. The better oxidation resistance of Mo-14Si-28B alloy is due to a sound and continuous B-SiO2 layer formation in the early stage of oxidation.
基金financially supported by the National Natu-ral Science Foundation of China(No.52105230)the Zhejiang Provincial Natural Science Foundation of China(No.LR21E050001)+1 种基金Zhoushan Municipal Science and Technology Research Program(No.2020C12007)Zhejiang Provincial Natural Science Foun-dation of China(No.LQ22E030019).
文摘In the marine environment,the protective coatings face serious corrosion and biofouling problem,lim-itations,and challenges that made self-healing coatings unable to perform both anti-corrosion and anti-biofouling dual-function at the same time.Here we constructed the corrosion resistance and anti-biofouling self-healing coating by integrating nano-containers into the coating matrix,the 2-Undecylimidazoline(ULM)acted as a corrosion inhibitor and anti-biofouling dual-functional agent which was loaded on the natural container attapulgite(ATP).To obtain high healing efficiency,a fluidity-driven self-healing silicone oil coating was thickened by fibrous ATP to enhance its stability,which played a key role in the self-healing and long-term corrosion resistance.The self-healing time of ULM@ATP rein-forced oil coating was 4 s at least in the air and up to 30 s in the 1 M HCl solution.Meanwhile,the ULM@ATP can significantly enhance the corrosion resistance of the self-healing coating,with the best effect achieved when the content of ULM@ATP was 5 wt.%.The impedance modulus of ULM@ATP-2 still reached 1.62×10^(8)Ωcm^(2) after 480 immersion in 3.5 wt.%NaCl solution,which is 3 orders of magnitude high than pure Oil coating(2.17×10^(5)Ωcm^(2)).The restructure of the ATP network and the release of ULM could largely inhibit the corrosion of metal.The continuous open circuit potential of the compos-ite coating performed the potentially infinite self-healing capacity.The self-healing performances of the composite coating in strong acid and base solutions exhibited high environmental suitability.This anti-corrosion and anti-biofouling(the surface coverage of adhered chlorella decreased 96.88%)dual-function strategy of self-healing coatings could be also realized by many other porous nano-materials or function modifications.The self-healing performances of the composite coating in strong acid and base solutions exhibited high environmental suitability.This anti-corrosion and anti-biofouling dual-function strategy of self-healing coatings could be also realized by many other porous nano-materials or function modifica-tions.The rapid response self-healing coating possessed anti-biofouling and active self-healing functions and showed wide application under more service environments.
文摘The study focused on investigating the effect of Deep Cryogenic Treatment(DCT)on the mechanical and ballistic properties of AA7075-T6 aluminum alloy.The microstructure,microhardness,tensile strength,and impact strength of the Base Material(BM)and DCT-treated 7075 samples were analyzed through metallographic analysis and mechanical tests.The microstructure of the DCT-treated 7075 samples revealed fine grains and a distribution of secondary phase particles.The tensile strength,impact strength,and microhardness of DCT-treated samples increased by 7.41%,4%,and 9.68%,respectively,compared to the BM samples.The fractography analysis of the tensile samples showed cleavage facets,microvoids,and dimples in both the samples.The ballistic behavior of the BM and DCT target plates were studied by impacting hard steel core projectiles at a velocity of 750±10 m/s.The target plates failed due to petaling and ductile hole enlargement,and the depth of penetration(DOP)of the DCT target was less than that of the BM target,indicating a higher ballistic resistance.The post-ballistic microstructure examination of the target plates showed the formation of an Adiabatic Shear Band(ASB)without any cracks.It was concluded that the DCT treatment improved the mechanical and ballistic properties of the aluminum alloy due to grain refinement and high dislocation density.
基金financially supported by the National Natural Science Foundation for Young Scholars of China(No.51401195)the National Basic Research Program of China(No.2011CB605506)
文摘Creep experiments of the TiAl alloy with high Nb content were conducted to consider both the temperature dependence and stress dependence of its creep behavior.The creep curves were characterized by Theta constitutive model,and Newton-Gauss method was applied to obtain the material parameters.Based on the rupture strain,the rupture life of the TiAl alloy was able to be predicted by Theta constitutive model.The results show that the creep curves of the TiAl alloy contain primary creep,secondary creep and tertiary creep stages,especially for the lower stress.The rupture life of the TiAl alloy decreases with the increase in either applied stress or temperature.Theta constitutive model is able to describe the creep deformation of the TiAl alloy accurately,and the predicted life agrees well with the experimental result.
基金the National Natural Science Foundation of China （No. 50471017）.
文摘The Hot deformation and martensitic transformation behaviors of Fe-32%Ni alloy was investigated by measurements of electrical resistance and X-ray diffraction. With the increase in strain, the austenite goes through from the work-hardened to the partial dynamcally re-crystallized and then to the completed dynamically re-crystallized. The martensitic transformation characteristics depend on the austenite states. The work-hardening in small strain is helpful to martensitic transformation due to the low dislocation density and little lattice distortion, while the high dislocation density and severe lattice distortion by the increase in strain will hinder the martensitic nucleation. Once dynamic re-crystallization （ DRX ） takes place, the martensitic transformation will be enhanced again, which is related to the heterogeneous dynamic substructures. The growing DRX grain can enhance the martensitic nucleation due to the low dislocation density near its grain boundary.
