Beryllium carbide is used in inertial confinement fusion(ICF)capsule ablation material due to its low atomic number,low opacity,and high melting point properties.We used the method of climbing image nudged elastic ban...Beryllium carbide is used in inertial confinement fusion(ICF)capsule ablation material due to its low atomic number,low opacity,and high melting point properties.We used the method of climbing image nudged elastic band(CINEB)to calculate the diffusion barrier of copper atom in the crystal of beryllium and beryllium carbide.The diffusion barrier of copper atom in crystal beryllium is only 0.79 eV,and the barrier in beryllium carbide is larger than 2.85 eV.The three structures of beryllium carbide:anti-fluorite Be2C,Be2C-Ⅰ,and Be2C-Ⅲhave a good blocking effect to the diffusion of copper atom.Among them,the Be2C-Ⅲstructure has the highest diffusion barrier of 6.09 eV.Our research can provide useful help for studying Cu diffusion barrier materials.展开更多
The effect of LPPS Ni_3Al-Y_2O_3 diffusion barrier layer on interdiffusion of elements between coating and substrate has been investigated.It was found that the retardation of interdiffusion is related to the amount o...The effect of LPPS Ni_3Al-Y_2O_3 diffusion barrier layer on interdiffusion of elements between coating and substrate has been investigated.It was found that the retardation of interdiffusion is related to the amount of oxide in the diffusion barrier layer.The retardation is not remark- able when the content of Y_2O_3 is 8 wt-%,whereas the diffusion of Al,Co or Cr has all been notably retarded when the content of Y_2O_3 reaches 30 wt-%.The retardation effect of diffu- sion barrier is different for different elements such as Al,Co or Cr.展开更多
NiCrAlY coatings are widely applied on various alloy components to enhance oxidation and/or corrosion resistance at high temperatures.However,elements interdiffusion occurs between them due to composition difference.A...NiCrAlY coatings are widely applied on various alloy components to enhance oxidation and/or corrosion resistance at high temperatures.However,elements interdiffusion occurs between them due to composition difference.Although various diffusion barriers(DBs)are reported,this problem is still far from completely solved as most ceramic barriers suffer from poor adherence,while the metallic barriers play a limited role.In this study,NiCrAlY coating was deposited onto a second-generation single-crystal superalloy by arc ion plating.A novel simple method is provided to address elements interdiffusion.By pre-oxidation at a moderate temperature,a thin scale of Ni(Co)O forms at the alloy surface.It transforms to be an alumina/NiCoCr alloy/alumina sandwich by an in-situ reaction with the overlaying NiCrAlY coating and the alloy substrate at high service temperatures,which offers good barrier ability in conjunction with strong adhesion.In the presence of such an alumina/alloy/alumina DB,the NiCrAlY coating provides high resistance to oxidation and scale spallation for the alloy substrate.展开更多
Skutterudite(SKD)thermoelectric materials have high conversion efficiency,great mechanical proper-ties,and economical practicability in the medium temperature range(500e550C).They need to bejoined with metal electrode...Skutterudite(SKD)thermoelectric materials have high conversion efficiency,great mechanical proper-ties,and economical practicability in the medium temperature range(500e550C).They need to bejoined with metal electrodes to form a thermoelectric power generation device during application.However,high contact resistivity,severe element diffusion,and large coefficient of thermal expansionmismatch are main obstacles for their applications.To address these issues,a FeCoNiCrMo high-entropyalloy diffusion barrier layer was designed and prepared using an arc smelting method in this paper.Effectof heating temperatures on the microstructure and properties of the bonded joints were investigated.The maximum shear strength was 21.6 Mpa and the corresponding reaction layer thickness,contactresistivity were 3.77 mm,1.8 mUcm2 respectively at 600C,40 MPa,10 min.Shear strength dropped downto 18.8 MPa and the contact resistivity increased to 4.2 mU cm2 after aging for 640 h.Numerical modelwas established and it predicted that the contact resistivity would keep lower than 6.5 mU cm2(300 h,100 days)and 11 mU cm2(8760 h,1 year)and the reaction layer thickness would not exceed 25 mm(2400 h,100 days)and 45 mm(8760 h,1 year).展开更多
The multi-layer metals of Ni/AuGe/Pt/Au with a Pt diffusion barrier layer of ohmic contact to n-GaAs were studied. The surface morphology and ohmic contact resistivity of multi-layer metals were characterized, with an...The multi-layer metals of Ni/AuGe/Pt/Au with a Pt diffusion barrier layer of ohmic contact to n-GaAs were studied. The surface morphology and ohmic contact resistivity of multi-layer metals were characterized, with and without the Pt diffusion barrier layer for comparison. The SEM and EDS measurements show the Pt diffusion barrier layer can block the interdiffusion of atoms in multi-layer metals, and improve the surface morphology. The TLM results show that the samples with a Pt diffusion barrier layer have uniform ohmic contact resistance, indicating that the Pt diffusion barrier layer can increase the repetition and uniformity of ohmic contact to n-GaAs, and improve the thermal stability and reliability of GaAs-based devices.展开更多
An oxidation-resistant composite coating,including Mo-Si-B layer and Al_(2)O_(3)diffusion barrier,was prepared on Nb-Si-based alloy by a two-step method.The Al_(2)O_(3)film was fabricated by firstly deposition of Al o...An oxidation-resistant composite coating,including Mo-Si-B layer and Al_(2)O_(3)diffusion barrier,was prepared on Nb-Si-based alloy by a two-step method.The Al_(2)O_(3)film was fabricated by firstly deposition of Al on the alloy through pack cementation,and then by in situ oxidation of the aluminide coating.Mo-Si-B coating was then prepared on the Al_(2)O_(3)film by spark plasma sintering.The Mo-Si-B coating is mainly composed of MoSi_(2)and a small amount of MoB and SiO_(2)particles.After long-term exposure at 1250℃,the growth of the interdiffusion zone(IDZ)was suppressed effectively at the interface with the Al_(2)O_(3)diffusion barrier.The results indicate that the diffusion barrier can significantly inhibit the outward diffusion of Nb,Ti and Cr alloying elements as well as the sluggish inward consumption of Si element.The Mo-Si-B coating with Al_(2)O_(3)diffusion barrier exhibited a good oxidation resistance with a mass gain of about 0.97 mg/cm^(2)after 500 h of oxidation.展开更多
A compact and adherent Al_(2)O_(3)diffusion barrier was obtained between a Ni coating and stainless steel 316(316SS)through double-pulse composite plating coupled with in-situ thermal growth.To promote the formation o...A compact and adherent Al_(2)O_(3)diffusion barrier was obtained between a Ni coating and stainless steel 316(316SS)through double-pulse composite plating coupled with in-situ thermal growth.To promote the formation ofα-Al_(2)O_(3)at low temperature,a Cr_(2)O_(3) film was firstly prepared by pre-oxidation of 316SS.Then a Ni-Al/NiO composite coating was deposited on 316SS in a modified Watts'bath with a Zeta potential of about+21.89 m V,a favorable condition for the co-deposition of double particles and nickel,followed by heat treatment in Ar at 800℃for 12 h.Results of diffusion resistance tests at 750 and 800℃for 100 h in Ar suggest that the Ni/α-Al_(2)O_(3)composite coating changes slightly during the annealing treatment and significantly prevents the diffusion of Fe and Cr from 316SS substrate to the upper Ni layer.Furthermore,corrosion resistance of the composite coating is higher than that of the 316SS/Ni sample.展开更多
A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductiv...A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductivity of barrier material were characterized.The results show that the samples exhibit the formation of cubic perovskite structure phase.The increase of Y-doping amount on A-site improved electrical conductivity and sinterability of materials.A limiting current oxygen sensor based on Y_(0.07)Sr_(0.97)Ti_(0.9)In_(0.1)O_(3–δ)as a dense diffusion barrier shows excellent sensing performance.The linear relationship between limiting current logIL and 1000/T can described logIL=4.603,8−3.847,5·1,000/T.At 750°C,0.25%≤x(O_(2))≤5.0%,the linear relationship between limiting current(IL)and oxygen amount(x(O_(2)))can described as I_(L)=7.047,6+3.875,1·x(O_(2)).展开更多
The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techni...The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techniques. The results indicate that the Pt diffusion barrier layer between the PZT layer and the Si substrate prohibits the formation of TiCx, TiSix and SiO2 species in the PZT layer. The Pt barrier layer also completly interrupts the diffusion of Si from the Si substrate into the PZT layer and impedes the diffusion of oxygen from air to the Si substrate greatly. Although the Pt layer can not prevent completely the diffusion and reaction between oxygen and silicon, it can prevent the formation of a stable SiO2 interface layer on the interface of PZT/Si. The Pt layer reacts with silicon to form PtSix species on the interface of Pt/Si, which can intensify the chemical binding strength between the Pt layer and the Si substrate. To play a good role as a diffusion barrier layer, the Pt barrier layer must be not thinner than 140 nm. The existence of the Pt layer not only promotes the crystallization of PZT layer to form a perovskite phase but also improves dielectric and ferroelectric performances of the PZT layer.展开更多
Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industrycontaminated s...Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industrycontaminated sites.This study aimed to investigate the gas diffusion barrier performance of compacted clayey soils amended with three agents including attapulgite and diatomite individually,and attapulgite/diatomite mixture.The properties including water retention,volumetric shrinkage,gas diffusion,and unconfined compressive strength were evaluated through a series of laboratory tests of amended compacted clayey soils.The results demonstrate that the decrease in volume proportions of interaggregate pores leads to an increase in unconfined compressive strength(qu).Both hydrophilic groups and microstructures of attapulgite and diatomite result in an increase in water retention percent(Wt)of compacted clayey soil specimens after amendment regardless of the type of agent or initial water content(w0).Furthermore,the ratio of the gas diffusion coefficient(De)to the gas diffusion coefficient in the air(Da)was significantly reduced owing to a decrease in volume proportions of inter-aggregate pores,hydrophilic group,and microstructures of attapulgite and diatomite.Scanning electron microscope analyses revealed that rod-shaped attapulgite filled the inter-aggregate pores formed by clay particles,whereas the disc-shaped diatomite particles,characterized by micropores,failed to obstruct the interaggregate pores due to their larger particle size.Mercury intrusion porosimetry(MIP)analyses showed a reduction in pore volume in the inter-aggregate pores,leading to a reduction in the total pore volume for both the attapulgite and attapulgite/diatomite mixture amended clays,which is in accordance with the scanning electron microscope(SEM)results.The findings are pertinent to the practical application of compacted clay liners as gas barriers against the upward migration of volatile or semi-volatile organic contaminants at contaminated sites.展开更多
Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decompos...Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that there is a thermodynamically favorable reaction at the SiO_2/Ta interface:37Ta+15SiO_2=5Ta_5Si_3+6Ta_2O_5.The more stable products Ta_5Si_3 and Ta_2O_5 may be beneficial to stop the diffusion of Cu into SiO_2.展开更多
To advance the application of layered oxide cathodes in fast-charging sodium-ion batteries,it is crucial to not only suppress irreversible phase transitions but also improve the rate capability of cathode materials an...To advance the application of layered oxide cathodes in fast-charging sodium-ion batteries,it is crucial to not only suppress irreversible phase transitions but also improve the rate capability of cathode materials and optimize Na^(+)diffusion kinetics to ensure high capacity output at various charge-discharge rates.In this research,the targeted F-substitution with a heavy ratio in oxygen anion layer optimizes the Na^(+)diffusion path and electronic conductivity of the material,thereby decreasing the Na^(+)diffusion barrier and imparting high-rate performance.At a 20 C rate,the cathode achieves a capacity of over 80 mAh g^(-1)with stable cycling performance.Additionally,the dual rivet effect between the transition metal layer and oxygen layer prevents significant phase transitions during charge/discharge within the 2-4.2 V range for the modified cathode.As a result,the F-substituted oxygen anion layer improved Na^(+)diffusion,electronic conductivity,and crystal plane structure stability,which led to the development of a highperformance,fast-charging sodium-ion battery(SIB),opening new avenues for commercial applications.展开更多
A low-diffusion Ni Re Pt Al coating((Ni,Pt)Al outer layer in addition to a Re-rich diffusion barrier layer)was prepared on a Ni_(3)Al-base single crystal(SC)superalloy via electroplating and gaseous aluminizing treatm...A low-diffusion Ni Re Pt Al coating((Ni,Pt)Al outer layer in addition to a Re-rich diffusion barrier layer)was prepared on a Ni_(3)Al-base single crystal(SC)superalloy via electroplating and gaseous aluminizing treatments,wherein the electroplating procedures consisted of the composite deposition of Ni-Re followed by electroplating of Pt.In order to perform a comparison with conventional Ni Al and(Ni,Pt)Al coatings,the cyclic oxidation performance of the Ni Re Pt Al coating was evaluated at 1100 and 1150℃.We observed that the oxidation resistance of the Ni Re Pt Al coating was significantly improved by the greater presence of the residualβ-Ni Al phase in the outer layer and the lesser outward-diffusion of Mo from the substrate.In addition,the coating with the Re-rich diffusion barrier demonstrated a lower extent of interdiffusion into the substrate,where the thickness of the second reaction zone(SRZ)in the substrate alloy decreased by 25%.The mechanisms responsible for improving the oxidation resistance and decreasing the extent of SRZ formation are discussed,in which a particular attention is paid to the inhibition of the outward diffusion of Mo by the Re-based diffusion barrier.展开更多
Diffusion barrier materials(DBMs)are critical for the stability and efficiency of thermoelectric devices.Conventional DBM selection via density functional theory(DFT)calculations is computationally intensive.Here,we i...Diffusion barrier materials(DBMs)are critical for the stability and efficiency of thermoelectric devices.Conventional DBM selection via density functional theory(DFT)calculations is computationally intensive.Here,we introduce an efficient screening approach that employs substitution energy as a surrogate for interfacial reaction energy,significantly reducing computational demand.By integrating substitution energy with migration energy barriers,we identify Ni as a robust DBM for Ag_(2)Se.Experimental validation confirms that Ni/Ag_(2)Se joints exhibit low contact resistivity(6.6μΩ·cm^(2))and high thermal stability after 30 days of thermal aging.The Te-free Ag_(2)Se/MgAgSb devices achieve a maximum cooling temperature difference of 68 K at 350 K,comparable to state-of-the-art Ag_(2)Se/Bi_(2)Te_(3) devices,while demonstrating excellent durability over 2000 power cycles.This strategy offers a rapid and reliable framework for DBM selection,accelerating the advancement of high-performance thermoelectric devices.展开更多
In this work,a modified approach for preparing CVD SiC fiber-reinforced superalloy matrix composites was rationally developed.The composites were fabricated by vacuum hot pressing(VHP)process using precursor wires coa...In this work,a modified approach for preparing CVD SiC fiber-reinforced superalloy matrix composites was rationally developed.The composites were fabricated by vacuum hot pressing(VHP)process using precursor wires coated with(Al+Al2O3)diffusion barrier layers and GH4169 superalloy coatings.BNi-7 brazing filler metals were introduced on the surface of precursor wires in order to decrease the temperature of the VHP process.It was found that the VHP temperature was reduced by about 100℃,and the melting,diffusion,nucleation and growth processes of BNi-7 fillers at 900?C motivated the recrystallization and plastic flow of the matrix under the increasing pressure,thereby a compact composite composed of intact SiC fibers and fine equiaxial grain structure superalloy matrix was achieved.Meanwhile,the elements were distributed homogeneously among the fibers in the composite and no interfacial reactions occurred.This method provides a new insight for designing and manufacturing high-quality composites in practical engineering.展开更多
A novel Re modifiedβ-(Ni,Pt)Al coating was prepared on a Mo-rich Ni_3 Al-based single crystal(SC)superalloy by electro-deposition of Re/Pt dual films and low-activity aluminizing.The isothermal oxidation behavior of ...A novel Re modifiedβ-(Ni,Pt)Al coating was prepared on a Mo-rich Ni_3 Al-based single crystal(SC)superalloy by electro-deposition of Re/Pt dual films and low-activity aluminizing.The isothermal oxidation behavior of the Re modifiedβ-(Ni,Pt)Al coating and traditionalβ-(Ni,Pt)Al coating was comparatively studied at 1100℃.Apparent spallation of oxide scale was found on the surface of traditionalβ-(Ni,Pt)Al coating after 300 h isothermal exposure,which mainly resulted from the evaporation of Mo-containing oxides.It is further found that the outward diffusion of Mo from the SC substrate was effectively inhibited in the Re modifiedβ-(Ni,Pt)Al coating by forming theσ-MoRe phase both at the coating/superalloy interface and grain boundaries.It is also revealed that the addition of Re can stabilise Mo to form theσ-MoRe phase,allowing the improved oxidation resistance of the Re modifiedβ-(Ni,Pt)Al coating.展开更多
Sodium(Na)metal batteries with a high volumetric energy density that can be operated at high rates are highly desirable.However,an uneven Na-ion migration in bulk Na anodes leads to localized deposition/dissolution of...Sodium(Na)metal batteries with a high volumetric energy density that can be operated at high rates are highly desirable.However,an uneven Na-ion migration in bulk Na anodes leads to localized deposition/dissolution of sodium during high-rate plating/stripping behaviors,followed by severe dendrite growth and loose stacking.Herein,we engineer the Na hybrid anode with sodiophilic Na_(3)Bi-penetration to develop the abundant phase-boundary ionic transport channels.Compared to intrinsic Na,the reduced adsorption energy and ion-diffusion barrier on Na_(3)Bi ensure even Na^(+)nucleation and rapid Na^(+)migration within the hybrid electrode,leading to uniform deposition and dissolution at high current densities.Furthermore,the bismuthide enables compact Na deposition within the sodiophilic framework during cycling,thus favoring a high volumetric capacity.Consequently,the obtained anode was endowed with a high current density(up to 5 mA∙cm^(−2)),high areal capacity(up to 5 mA∙h∙cm^(−2)),and long-term cycling stability(up to 2800 h at 2 mA∙cm^(−2)).展开更多
Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology develop...Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.展开更多
An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ions.Here,we propose a simple and efficient method...An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ions.Here,we propose a simple and efficient method for searching potential K cathode materials with first principles calculations.Our screening is based on combinations of weight capacity,K ion occupation ratio,volume change per K,and valence limit.With this screening method we predicted a series of potential K ions cathodes with favorable electrochemical performance,such as K_(2)VPO_(4)CO_(3)-like structures with 1 D diffusion channels,3 D channel structures K_(2)CoSiO_(4),layered materials KCoO_(2),KCrO_(2),KVF_(4) and K_(5)V_(3)F_(14),and others.These potential cathodes have small volume changes,suitable voltage,and high capacity,with small diffusion barriers.They may be useful in K-ion batteries with high energy density and rate performance.展开更多
Internal reformation of low steam methane fuel is highly beneficial for improving the energy efficiency and reducing the system complexity and cost of solid oxide fuel cells(SOFCs).However,anode coking for the Ni-base...Internal reformation of low steam methane fuel is highly beneficial for improving the energy efficiency and reducing the system complexity and cost of solid oxide fuel cells(SOFCs).However,anode coking for the Ni-based anode should be prevented before the technology becomes a reality.A multi-physics fully coupled model is employed to simulate the operations of SOFCs fueled by low steam methane.The multi-physics model produces I-V relations that are in excellent agreement with the experimental results.The multi-physics model and the experimental non-coking current density deduced kinetic carbon activity criterion are used to examine the effect of operating parameters and the anode diffusion barrier layer on the propensity of carbon deposition.The interplays among the fuel utilization ratio,current generation,thickness of the barrier layer and the cell operating voltage are revealed.It is demonstrated that a barrier layer of 400μm thickness is an optimal and safe anode design to achieve high power density and non-coking operations.The anode structure design can be very useful for the development of high efficiency and low cost SOFC technology.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974253 and 11774248)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2017YFA0303600)
文摘Beryllium carbide is used in inertial confinement fusion(ICF)capsule ablation material due to its low atomic number,low opacity,and high melting point properties.We used the method of climbing image nudged elastic band(CINEB)to calculate the diffusion barrier of copper atom in the crystal of beryllium and beryllium carbide.The diffusion barrier of copper atom in crystal beryllium is only 0.79 eV,and the barrier in beryllium carbide is larger than 2.85 eV.The three structures of beryllium carbide:anti-fluorite Be2C,Be2C-Ⅰ,and Be2C-Ⅲhave a good blocking effect to the diffusion of copper atom.Among them,the Be2C-Ⅲstructure has the highest diffusion barrier of 6.09 eV.Our research can provide useful help for studying Cu diffusion barrier materials.
文摘The effect of LPPS Ni_3Al-Y_2O_3 diffusion barrier layer on interdiffusion of elements between coating and substrate has been investigated.It was found that the retardation of interdiffusion is related to the amount of oxide in the diffusion barrier layer.The retardation is not remark- able when the content of Y_2O_3 is 8 wt-%,whereas the diffusion of Al,Co or Cr has all been notably retarded when the content of Y_2O_3 reaches 30 wt-%.The retardation effect of diffu- sion barrier is different for different elements such as Al,Co or Cr.
基金financially supported by the National Natural Science Foundation of China(No.51671053)the Natural Science Foundation of Liaoning Province of China(No.2019-ZD-0264)the Ministry of Industry and Information Technology Project(No.MJ-2017-J-99)。
文摘NiCrAlY coatings are widely applied on various alloy components to enhance oxidation and/or corrosion resistance at high temperatures.However,elements interdiffusion occurs between them due to composition difference.Although various diffusion barriers(DBs)are reported,this problem is still far from completely solved as most ceramic barriers suffer from poor adherence,while the metallic barriers play a limited role.In this study,NiCrAlY coating was deposited onto a second-generation single-crystal superalloy by arc ion plating.A novel simple method is provided to address elements interdiffusion.By pre-oxidation at a moderate temperature,a thin scale of Ni(Co)O forms at the alloy surface.It transforms to be an alumina/NiCoCr alloy/alumina sandwich by an in-situ reaction with the overlaying NiCrAlY coating and the alloy substrate at high service temperatures,which offers good barrier ability in conjunction with strong adhesion.In the presence of such an alumina/alloy/alumina DB,the NiCrAlY coating provides high resistance to oxidation and scale spallation for the alloy substrate.
基金The authors gratefully acknowledge National Natural Science Foundation of China[Grant No.51805113 and 51775142]National Key R&D Program of China[2019YFA0705201]+2 种基金China Postdoctoral Science Foundation funded project[Grant No.2020T130143,2018M631923]Fundamental Research Funds for the Central Uni-versities[Grant No.FRFCU5710050920]Heilongjiang Touyan Team[XNAUEA 5640202520]。
文摘Skutterudite(SKD)thermoelectric materials have high conversion efficiency,great mechanical proper-ties,and economical practicability in the medium temperature range(500e550C).They need to bejoined with metal electrodes to form a thermoelectric power generation device during application.However,high contact resistivity,severe element diffusion,and large coefficient of thermal expansionmismatch are main obstacles for their applications.To address these issues,a FeCoNiCrMo high-entropyalloy diffusion barrier layer was designed and prepared using an arc smelting method in this paper.Effectof heating temperatures on the microstructure and properties of the bonded joints were investigated.The maximum shear strength was 21.6 Mpa and the corresponding reaction layer thickness,contactresistivity were 3.77 mm,1.8 mUcm2 respectively at 600C,40 MPa,10 min.Shear strength dropped downto 18.8 MPa and the contact resistivity increased to 4.2 mU cm2 after aging for 640 h.Numerical modelwas established and it predicted that the contact resistivity would keep lower than 6.5 mU cm2(300 h,100 days)and 11 mU cm2(8760 h,1 year)and the reaction layer thickness would not exceed 25 mm(2400 h,100 days)and 45 mm(8760 h,1 year).
基金Project supported by the National Natural Science Foundation of China(No.11474036)the National Key Laboratory of High Power Semiconductor Lasers Foundations(No.9140C310103120C31114)
文摘The multi-layer metals of Ni/AuGe/Pt/Au with a Pt diffusion barrier layer of ohmic contact to n-GaAs were studied. The surface morphology and ohmic contact resistivity of multi-layer metals were characterized, with and without the Pt diffusion barrier layer for comparison. The SEM and EDS measurements show the Pt diffusion barrier layer can block the interdiffusion of atoms in multi-layer metals, and improve the surface morphology. The TLM results show that the samples with a Pt diffusion barrier layer have uniform ohmic contact resistance, indicating that the Pt diffusion barrier layer can increase the repetition and uniformity of ohmic contact to n-GaAs, and improve the thermal stability and reliability of GaAs-based devices.
基金financially supported by the National Natural Science Foundation of China (Nos. 51971177 and 51971181)the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2020JM-106)
文摘An oxidation-resistant composite coating,including Mo-Si-B layer and Al_(2)O_(3)diffusion barrier,was prepared on Nb-Si-based alloy by a two-step method.The Al_(2)O_(3)film was fabricated by firstly deposition of Al on the alloy through pack cementation,and then by in situ oxidation of the aluminide coating.Mo-Si-B coating was then prepared on the Al_(2)O_(3)film by spark plasma sintering.The Mo-Si-B coating is mainly composed of MoSi_(2)and a small amount of MoB and SiO_(2)particles.After long-term exposure at 1250℃,the growth of the interdiffusion zone(IDZ)was suppressed effectively at the interface with the Al_(2)O_(3)diffusion barrier.The results indicate that the diffusion barrier can significantly inhibit the outward diffusion of Nb,Ti and Cr alloying elements as well as the sluggish inward consumption of Si element.The Mo-Si-B coating with Al_(2)O_(3)diffusion barrier exhibited a good oxidation resistance with a mass gain of about 0.97 mg/cm^(2)after 500 h of oxidation.
基金financially supported by the Specific Research Project of Guangxi for Research Bases and Talents(No.GuiKe AD20159074)the National Natural Science Foundation of China(No.51801035)the Natural Science Foundation of Guangxi Province(No.2021GXNSFAA220118)
文摘A compact and adherent Al_(2)O_(3)diffusion barrier was obtained between a Ni coating and stainless steel 316(316SS)through double-pulse composite plating coupled with in-situ thermal growth.To promote the formation ofα-Al_(2)O_(3)at low temperature,a Cr_(2)O_(3) film was firstly prepared by pre-oxidation of 316SS.Then a Ni-Al/NiO composite coating was deposited on 316SS in a modified Watts'bath with a Zeta potential of about+21.89 m V,a favorable condition for the co-deposition of double particles and nickel,followed by heat treatment in Ar at 800℃for 12 h.Results of diffusion resistance tests at 750 and 800℃for 100 h in Ar suggest that the Ni/α-Al_(2)O_(3)composite coating changes slightly during the annealing treatment and significantly prevents the diffusion of Fe and Cr from 316SS substrate to the upper Ni layer.Furthermore,corrosion resistance of the composite coating is higher than that of the 316SS/Ni sample.
基金supported by the National Natural Science Foundation of China(Nos.51962004 and 51562009).
文摘A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductivity of barrier material were characterized.The results show that the samples exhibit the formation of cubic perovskite structure phase.The increase of Y-doping amount on A-site improved electrical conductivity and sinterability of materials.A limiting current oxygen sensor based on Y_(0.07)Sr_(0.97)Ti_(0.9)In_(0.1)O_(3–δ)as a dense diffusion barrier shows excellent sensing performance.The linear relationship between limiting current logIL and 1000/T can described logIL=4.603,8−3.847,5·1,000/T.At 750°C,0.25%≤x(O_(2))≤5.0%,the linear relationship between limiting current(IL)and oxygen amount(x(O_(2)))can described as I_(L)=7.047,6+3.875,1·x(O_(2)).
基金Project supported by the 1997 Grant-in Aid for Scientific Fundament Research of Tsinghua University and by State Key Laboratory of Rare Earth Materials Chemistry and Application.
文摘The effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techniques. The results indicate that the Pt diffusion barrier layer between the PZT layer and the Si substrate prohibits the formation of TiCx, TiSix and SiO2 species in the PZT layer. The Pt barrier layer also completly interrupts the diffusion of Si from the Si substrate into the PZT layer and impedes the diffusion of oxygen from air to the Si substrate greatly. Although the Pt layer can not prevent completely the diffusion and reaction between oxygen and silicon, it can prevent the formation of a stable SiO2 interface layer on the interface of PZT/Si. The Pt layer reacts with silicon to form PtSix species on the interface of Pt/Si, which can intensify the chemical binding strength between the Pt layer and the Si substrate. To play a good role as a diffusion barrier layer, the Pt barrier layer must be not thinner than 140 nm. The existence of the Pt layer not only promotes the crystallization of PZT layer to form a perovskite phase but also improves dielectric and ferroelectric performances of the PZT layer.
基金the funding support from the National Natural Science Foundation of China(Grant No.42177133)the Primary Research and Development Plan of Jiangsu Province(Grant No.BE2022830)the Primary Research and Development Plan of Anhui Province(Grant No.2023t07020018).
文摘Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industrycontaminated sites.This study aimed to investigate the gas diffusion barrier performance of compacted clayey soils amended with three agents including attapulgite and diatomite individually,and attapulgite/diatomite mixture.The properties including water retention,volumetric shrinkage,gas diffusion,and unconfined compressive strength were evaluated through a series of laboratory tests of amended compacted clayey soils.The results demonstrate that the decrease in volume proportions of interaggregate pores leads to an increase in unconfined compressive strength(qu).Both hydrophilic groups and microstructures of attapulgite and diatomite result in an increase in water retention percent(Wt)of compacted clayey soil specimens after amendment regardless of the type of agent or initial water content(w0).Furthermore,the ratio of the gas diffusion coefficient(De)to the gas diffusion coefficient in the air(Da)was significantly reduced owing to a decrease in volume proportions of inter-aggregate pores,hydrophilic group,and microstructures of attapulgite and diatomite.Scanning electron microscope analyses revealed that rod-shaped attapulgite filled the inter-aggregate pores formed by clay particles,whereas the disc-shaped diatomite particles,characterized by micropores,failed to obstruct the interaggregate pores due to their larger particle size.Mercury intrusion porosimetry(MIP)analyses showed a reduction in pore volume in the inter-aggregate pores,leading to a reduction in the total pore volume for both the attapulgite and attapulgite/diatomite mixture amended clays,which is in accordance with the scanning electron microscope(SEM)results.The findings are pertinent to the practical application of compacted clay liners as gas barriers against the upward migration of volatile or semi-volatile organic contaminants at contaminated sites.
文摘Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that there is a thermodynamically favorable reaction at the SiO_2/Ta interface:37Ta+15SiO_2=5Ta_5Si_3+6Ta_2O_5.The more stable products Ta_5Si_3 and Ta_2O_5 may be beneficial to stop the diffusion of Cu into SiO_2.
基金supported by the National Natural Science Foundation of China(Nos.22178221,22208221)the Shenzhen Science and Technology Program(Nos.JCYJ20220818095805012,JCYJ20230808105109019)+2 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515011078,2024A1515011507)the Scientific Foundation for Youth Scholars of Shenzhen University(868-000001032522,827-0001004)the Instrumental Analysis Center of Shenzhen University for the assistance with the Electron Microscope technical support。
文摘To advance the application of layered oxide cathodes in fast-charging sodium-ion batteries,it is crucial to not only suppress irreversible phase transitions but also improve the rate capability of cathode materials and optimize Na^(+)diffusion kinetics to ensure high capacity output at various charge-discharge rates.In this research,the targeted F-substitution with a heavy ratio in oxygen anion layer optimizes the Na^(+)diffusion path and electronic conductivity of the material,thereby decreasing the Na^(+)diffusion barrier and imparting high-rate performance.At a 20 C rate,the cathode achieves a capacity of over 80 mAh g^(-1)with stable cycling performance.Additionally,the dual rivet effect between the transition metal layer and oxygen layer prevents significant phase transitions during charge/discharge within the 2-4.2 V range for the modified cathode.As a result,the F-substituted oxygen anion layer improved Na^(+)diffusion,electronic conductivity,and crystal plane structure stability,which led to the development of a highperformance,fast-charging sodium-ion battery(SIB),opening new avenues for commercial applications.
基金the Key-Area Research and Development Program of Guangdong Province(2019B010936001)financially supported by the National Natural Science Foundation of China(Grant Nos.51671202 and 51301184)。
文摘A low-diffusion Ni Re Pt Al coating((Ni,Pt)Al outer layer in addition to a Re-rich diffusion barrier layer)was prepared on a Ni_(3)Al-base single crystal(SC)superalloy via electroplating and gaseous aluminizing treatments,wherein the electroplating procedures consisted of the composite deposition of Ni-Re followed by electroplating of Pt.In order to perform a comparison with conventional Ni Al and(Ni,Pt)Al coatings,the cyclic oxidation performance of the Ni Re Pt Al coating was evaluated at 1100 and 1150℃.We observed that the oxidation resistance of the Ni Re Pt Al coating was significantly improved by the greater presence of the residualβ-Ni Al phase in the outer layer and the lesser outward-diffusion of Mo from the substrate.In addition,the coating with the Re-rich diffusion barrier demonstrated a lower extent of interdiffusion into the substrate,where the thickness of the second reaction zone(SRZ)in the substrate alloy decreased by 25%.The mechanisms responsible for improving the oxidation resistance and decreasing the extent of SRZ formation are discussed,in which a particular attention is paid to the inhibition of the outward diffusion of Mo by the Re-based diffusion barrier.
基金supported by the National Natural Science Foundation of China(Nos.U21A2054,51961011,and 52273285)financial support from the Australian Research Council,HBIS Group-University of Queensland(HBIS-UQ)Innovation Centre for Sustainable Steel project'the Queensland University of Technology(QUT)Capacity Building Professor Program.
文摘Diffusion barrier materials(DBMs)are critical for the stability and efficiency of thermoelectric devices.Conventional DBM selection via density functional theory(DFT)calculations is computationally intensive.Here,we introduce an efficient screening approach that employs substitution energy as a surrogate for interfacial reaction energy,significantly reducing computational demand.By integrating substitution energy with migration energy barriers,we identify Ni as a robust DBM for Ag_(2)Se.Experimental validation confirms that Ni/Ag_(2)Se joints exhibit low contact resistivity(6.6μΩ·cm^(2))and high thermal stability after 30 days of thermal aging.The Te-free Ag_(2)Se/MgAgSb devices achieve a maximum cooling temperature difference of 68 K at 350 K,comparable to state-of-the-art Ag_(2)Se/Bi_(2)Te_(3) devices,while demonstrating excellent durability over 2000 power cycles.This strategy offers a rapid and reliable framework for DBM selection,accelerating the advancement of high-performance thermoelectric devices.
基金financially supported by the National Natural Science Foundation of China(No.51371170)。
文摘In this work,a modified approach for preparing CVD SiC fiber-reinforced superalloy matrix composites was rationally developed.The composites were fabricated by vacuum hot pressing(VHP)process using precursor wires coated with(Al+Al2O3)diffusion barrier layers and GH4169 superalloy coatings.BNi-7 brazing filler metals were introduced on the surface of precursor wires in order to decrease the temperature of the VHP process.It was found that the VHP temperature was reduced by about 100℃,and the melting,diffusion,nucleation and growth processes of BNi-7 fillers at 900?C motivated the recrystallization and plastic flow of the matrix under the increasing pressure,thereby a compact composite composed of intact SiC fibers and fine equiaxial grain structure superalloy matrix was achieved.Meanwhile,the elements were distributed homogeneously among the fibers in the composite and no interfacial reactions occurred.This method provides a new insight for designing and manufacturing high-quality composites in practical engineering.
基金financially supported by the National Science and Technology Major Project(Nos.2017-VI-0010-0081 and 2017-VI-0002-0072)the National Natural Science Foundation of China(Nos.51590894 and 51901107)+1 种基金the Beijing Natural Science Foundation(No.2194078)the“111 Project”(No.B17002)。
文摘A novel Re modifiedβ-(Ni,Pt)Al coating was prepared on a Mo-rich Ni_3 Al-based single crystal(SC)superalloy by electro-deposition of Re/Pt dual films and low-activity aluminizing.The isothermal oxidation behavior of the Re modifiedβ-(Ni,Pt)Al coating and traditionalβ-(Ni,Pt)Al coating was comparatively studied at 1100℃.Apparent spallation of oxide scale was found on the surface of traditionalβ-(Ni,Pt)Al coating after 300 h isothermal exposure,which mainly resulted from the evaporation of Mo-containing oxides.It is further found that the outward diffusion of Mo from the SC substrate was effectively inhibited in the Re modifiedβ-(Ni,Pt)Al coating by forming theσ-MoRe phase both at the coating/superalloy interface and grain boundaries.It is also revealed that the addition of Re can stabilise Mo to form theσ-MoRe phase,allowing the improved oxidation resistance of the Re modifiedβ-(Ni,Pt)Al coating.
基金supported by the National Natural Science Foundation of China (21938005 and 21776197)Key Laboratory of Coal Science and Technology, Education Ministry and Shanxi Province, Taiyuan University of Technology
文摘Sodium(Na)metal batteries with a high volumetric energy density that can be operated at high rates are highly desirable.However,an uneven Na-ion migration in bulk Na anodes leads to localized deposition/dissolution of sodium during high-rate plating/stripping behaviors,followed by severe dendrite growth and loose stacking.Herein,we engineer the Na hybrid anode with sodiophilic Na_(3)Bi-penetration to develop the abundant phase-boundary ionic transport channels.Compared to intrinsic Na,the reduced adsorption energy and ion-diffusion barrier on Na_(3)Bi ensure even Na^(+)nucleation and rapid Na^(+)migration within the hybrid electrode,leading to uniform deposition and dissolution at high current densities.Furthermore,the bismuthide enables compact Na deposition within the sodiophilic framework during cycling,thus favoring a high volumetric capacity.Consequently,the obtained anode was endowed with a high current density(up to 5 mA∙cm^(−2)),high areal capacity(up to 5 mA∙h∙cm^(−2)),and long-term cycling stability(up to 2800 h at 2 mA∙cm^(−2)).
基金This work was supported by the National Basic Research Program of China （No.2012CB215405）, the National Natural Science Foundation of China （No.11374272）, and the Specialized Research Fund for the Doctoral Program of Higher Education （No.20123402110064）.
文摘Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.
基金supported by the National Key R&D Program of China(Grant No.2016YFA0200400)the National Natural Science Foundation of China(Grant No.11504123 and No.51627805)。
文摘An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ions.Here,we propose a simple and efficient method for searching potential K cathode materials with first principles calculations.Our screening is based on combinations of weight capacity,K ion occupation ratio,volume change per K,and valence limit.With this screening method we predicted a series of potential K ions cathodes with favorable electrochemical performance,such as K_(2)VPO_(4)CO_(3)-like structures with 1 D diffusion channels,3 D channel structures K_(2)CoSiO_(4),layered materials KCoO_(2),KCrO_(2),KVF_(4) and K_(5)V_(3)F_(14),and others.These potential cathodes have small volume changes,suitable voltage,and high capacity,with small diffusion barriers.They may be useful in K-ion batteries with high energy density and rate performance.
基金supported by the National Natural Science Foundation of China (No.11574284 abd No.11774324)the National Basic Research Program of China (No.2012CB215405)Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Internal reformation of low steam methane fuel is highly beneficial for improving the energy efficiency and reducing the system complexity and cost of solid oxide fuel cells(SOFCs).However,anode coking for the Ni-based anode should be prevented before the technology becomes a reality.A multi-physics fully coupled model is employed to simulate the operations of SOFCs fueled by low steam methane.The multi-physics model produces I-V relations that are in excellent agreement with the experimental results.The multi-physics model and the experimental non-coking current density deduced kinetic carbon activity criterion are used to examine the effect of operating parameters and the anode diffusion barrier layer on the propensity of carbon deposition.The interplays among the fuel utilization ratio,current generation,thickness of the barrier layer and the cell operating voltage are revealed.It is demonstrated that a barrier layer of 400μm thickness is an optimal and safe anode design to achieve high power density and non-coking operations.The anode structure design can be very useful for the development of high efficiency and low cost SOFC technology.
