Hf xTa 1-xC-based ceramics exhibit exceptional thermodynamic stability under extreme temperatures. However, their intrinsic brittleness raises significant concerns about their safe service in extreme environments. Her...Hf xTa 1-xC-based ceramics exhibit exceptional thermodynamic stability under extreme temperatures. However, their intrinsic brittleness raises significant concerns about their safe service in extreme environments. Here, we designed and fabricated HfTaC/W_(2) dual-phase ceramics with robust interface bonding through induction plasma spheroidization. During in situ transmission electron microscopy(TEM) mechanical testing, the dual-phase ceramics exhibited plastic deformation with a fracture strength of(7.6 ± 1.2) GPa and a strain of 23.8% ± 0.18% in nanopillar compression, and a fracture strain of 6.2% under tensile loading. The mechanism of plastic deformation in both compression and tensile tests is attributed to the interactions between dislocations and dual-phase interfaces, as well as the dislocation movement inside the W phase. Thus, our work demonstrates the enhanced plasticity of dual-phase HfTaC_(2)/W with a W network embedded in the HfTaC_(2) matrix than singlephase HfTaC_(2) and provides a paradigm for the development of advanced ceramics that combine strength with enhanced ductility for both functional and structural applications.展开更多
The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ...The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ oxygen-passivated WS_(2) lubricating film(W–S–Ti–O composite film) was deposited to withstand AO irradiation. The structural and tribological evolution of the film was examined after a six-month space exposure experiment conducted outside the Chinese Space Station. The results show that in situ oxygen passivation of sulfur vacancies in the WS_(2) film promoted the formation of a dominant WS_(x)O_(y) phase within the W–S–Ti–O composite film. This phase effectively suppressed excessive WO_(3) formation during prolonged AO exposure while maintaining a low friction coefficient. After space exposure, the film exhibited a low friction coefficient and a wear life exceeding 4.5 × 10^(5) cycles. This performance is attributed to two main factors:(1) the presence of friction-induced spherical WO_(3) nanoparticles(approximately 11 nm) embedded in the transfer film, which promoted a transition from pure sliding to a mixed rolling–sliding regime;and(2) the retention of oriented WS_(2)(002) crystalline layers in the tribofilm, which mitigated the plowing effect of nanoparticles and prevented a significant increase in the wear rate.展开更多
Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding str...Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.展开更多
The microstructural characteristic of 1070AI matrix composites reinforced by 0.15 祄 AI2O3 particles whose volume fraction was 40% was investigated by TEM and HREM. The results showed that the interface between the ma...The microstructural characteristic of 1070AI matrix composites reinforced by 0.15 祄 AI2O3 particles whose volume fraction was 40% was investigated by TEM and HREM. The results showed that the interface between the matrix and reinforcements was clean and bonded well, without any interfacial reaction products. There were some preferential crystallographic orientation relationships between Al matrix and AI2O3 particle because of the lattice imperfection on the surface of Al2O3 particles.展开更多
Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings.Previous studies showe...Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings.Previous studies showed that the violence of coal specimen failure depends on both the interface friction and width-to-height（W/H） ratio of coal specimen. The mode of failure for a uniaxially loaded coal specimen or a coal pillar is a combination of both shear failure along the interface and compressive failure in the coal. The shear failure along the interface triggered the compressive failure in coal. The compressive failure of a coal specimen or a coal pillar can be controlled by changing its W/H ratio. As the W/H ratio increases, the ultimate strength increases. Hence, with a proper combination of interface friction and the W/H ratio of pillar or coal specimen, the mode of failure will change from sudden violent failure which is brittle failure to non-violent failure which is ductile failure. The main objective of this paper is to determine at what W/H ratio and interface friction the mode of failure changes from violent to non-violent. In this research, coal specimens of W/H ratio ranging from 1 to 10 were uniaxially tested under two interface frictions of 0.1 and 0.25, and the results are presented and discussed.展开更多
Explosion welding was carried out on the basis of vacuum hot melt W/CuCrZr composite plate.Metallurgical microscope,scanning electron microscope and energy dispersive X-ray spectroscope were used to observe the micros...Explosion welding was carried out on the basis of vacuum hot melt W/CuCrZr composite plate.Metallurgical microscope,scanning electron microscope and energy dispersive X-ray spectroscope were used to observe the microscopic morphology of the bonding interface.At the same time,combined with finite element calculations,the evolution mechanism of the interface of the hot melt explosion welded W/CuCrZr composite plate was explored.The results show that the interface bonding of the hot melt explosion welded W/CuCrZr composite plate is good and there is a cross-melting zone with 3–8μm in thickness,but cracks are developed on the W side.The numerical simulation reproduces the changes of pressure,stress,strain and internal energy at the bonding interface in the process of hot melt explosion welding.The location of the crack generated in the experiment coincides with the high stress position calculated by numerical simulation.The high pressure and high temperature near the hot melt explosion welding interface further promote the bonding of the interface.展开更多
The concept of effective concentration of surfaetant in membrane phase has been proposed,considering the high ad-sorption density of the surfactant at the droplet interfaces in LSM system.The effective concentration o...The concept of effective concentration of surfaetant in membrane phase has been proposed,considering the high ad-sorption density of the surfactant at the droplet interfaces in LSM system.The effective concentration of surfactant,C<sub>2</sub>,can be estimated by Eq.（7）—（9）.The swelling caused by emulsification during the initial dispersion process was investigated.The swelling rate wasmeasured by a density method.A model for estimating the"Emulsification" swelling rate,F<sub>se</sub>,has been proposed,basedon a mechanism of swelling due to the entrainment of water resulted from the interracial turbulence and emulsification inthe initial dispersion process.It has been found that Eq.（26）gives excellent fit to the experimental data of Fujinawa,etal.and of the authors.展开更多
The film forming behavior on the interface between air and hydrosol of Fe2O3 nanoparticles was investigated by the surface pressure-time isotherms, the surface pressure-trough area isotherms, Brewster angle microscopy...The film forming behavior on the interface between air and hydrosol of Fe2O3 nanoparticles was investigated by the surface pressure-time isotherms, the surface pressure-trough area isotherms, Brewster angle microscopy and transmission electron microscopy. It is found that the freshly prepared hydrosol of Fe2O3 nanoparticles is not stable. The surface pressure increases with the aging time and finally approaches a constant, and the smaller the concentration is, the smaller the surface pressure is stabilized at and the shorter the time the hydrosol reaching stable needs. The surface pressure also increases with compression until collapsed, and the longer the hydrosol is aged, the higher the collapsing pressure is. A uniform and compact film composed of nanoparticles with an average diameter of about 2-3 nm on the air-hydrosol interface is observed by Brewster angle microscope and transmission electron microscope.展开更多
With increasing usage of a web services today, user required to consecrate reasoning energy to learning the complexities of the interface as opposed to the content. Interface complexity measures the degree of complexi...With increasing usage of a web services today, user required to consecrate reasoning energy to learning the complexities of the interface as opposed to the content. Interface complexity measures the degree of complexity encountered between the user and digital medium like website. This paper presents a New Interface Complexity (NIC) Metric, which partially based on existing schema metrics to weigh human insight of recent service interface;taking into account elements and attributes of XML documents implemented in?World Wide Web Consortium (W3C) XML Schema (WXS) to reduce the structure affecting the effort for comprehending schema documents. The NIC metric is able to draw conclusions about the perceived qualities: interoperability, extensibility and flexibility. It was discovered that there are significant correlations between NIC metric and existing measures. Automating, this practice would be beneficial to developers and designers, as it would help to provide useful feedback in software project design to check the quality of documents for easy maintenance and properly used of XML data for distributed applications.展开更多
This paper describes the invesligation of the transfer behaviour of the alkaline earth-metal cations across the water/nitrobenzene interface facilitated by josamycin in the nitrobenzene phase using semi-differential c...This paper describes the invesligation of the transfer behaviour of the alkaline earth-metal cations across the water/nitrobenzene interface facilitated by josamycin in the nitrobenzene phase using semi-differential cyclic voltammetry .The peak height is directly proportional to the concentration of josaycin (nb) and to the potential scan rate.The complexes formed from alkaline earth-metal ions and josamycin at the w/nb interface are ML2^2+ ion.展开更多
The transfer of Sr^2+ and Ba^2+ ion,facilitated by 18-crown-6 present in the aqueous phase,and of succinylcholine ion at w/nb interface were investigated by semi-differeniial cyclic voltammetry.A good polarographic cu...The transfer of Sr^2+ and Ba^2+ ion,facilitated by 18-crown-6 present in the aqueous phase,and of succinylcholine ion at w/nb interface were investigated by semi-differeniial cyclic voltammetry.A good polarographic curve of succinylcholine ion dissolved in water was obtained in the system of 0.01 mol/l LiCl(w)-0.01mol/l TBATPB(nb).The peak current is directly proportional to the concentration of SC^2+ ion.It can be used for the determination of SC and the detection limit is 1.05×10^-5mol/l,The apparent D^m and D^mb have been estimated.The transfer of Sr^2+ and of Ba^2+ at the interface are facilitated by 18-Crown-6 present in the aqueous phase and the peak current is directly proportional to the concentration of 18-Crown-6 in water.This method can be used for the determination of the complexing agent and for the stability constant of the complex formed in the aqueous phase.All the experimental results are in keeping with the theoretical.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12202330,52501055)the Fundamental Research Funds for the Central Universities and the Innovation Fund of Xidian University (Grant No.YJSJ25017)the Natural Science Basic Research Program of Shaanxi (Grant No.2024JC-YBQN-0459)。
文摘Hf xTa 1-xC-based ceramics exhibit exceptional thermodynamic stability under extreme temperatures. However, their intrinsic brittleness raises significant concerns about their safe service in extreme environments. Here, we designed and fabricated HfTaC/W_(2) dual-phase ceramics with robust interface bonding through induction plasma spheroidization. During in situ transmission electron microscopy(TEM) mechanical testing, the dual-phase ceramics exhibited plastic deformation with a fracture strength of(7.6 ± 1.2) GPa and a strain of 23.8% ± 0.18% in nanopillar compression, and a fracture strain of 6.2% under tensile loading. The mechanism of plastic deformation in both compression and tensile tests is attributed to the interactions between dislocations and dual-phase interfaces, as well as the dislocation movement inside the W phase. Thus, our work demonstrates the enhanced plasticity of dual-phase HfTaC_(2)/W with a W network embedded in the HfTaC_(2) matrix than singlephase HfTaC_(2) and provides a paradigm for the development of advanced ceramics that combine strength with enhanced ductility for both functional and structural applications.
基金financially supported by the Space Utilization System of China Manned Space Engineering (Grant No.KJZ-YY-WCL05)。
文摘The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ oxygen-passivated WS_(2) lubricating film(W–S–Ti–O composite film) was deposited to withstand AO irradiation. The structural and tribological evolution of the film was examined after a six-month space exposure experiment conducted outside the Chinese Space Station. The results show that in situ oxygen passivation of sulfur vacancies in the WS_(2) film promoted the formation of a dominant WS_(x)O_(y) phase within the W–S–Ti–O composite film. This phase effectively suppressed excessive WO_(3) formation during prolonged AO exposure while maintaining a low friction coefficient. After space exposure, the film exhibited a low friction coefficient and a wear life exceeding 4.5 × 10^(5) cycles. This performance is attributed to two main factors:(1) the presence of friction-induced spherical WO_(3) nanoparticles(approximately 11 nm) embedded in the transfer film, which promoted a transition from pure sliding to a mixed rolling–sliding regime;and(2) the retention of oriented WS_(2)(002) crystalline layers in the tribofilm, which mitigated the plowing effect of nanoparticles and prevented a significant increase in the wear rate.
基金supported by the National Key R&D Program of China (No. 2018YFA0707300)the National Natural Science Foundation of China (No. 52374376)the Introduction Plan for High end Foreign Experts, China (No. G2023105001L)。
文摘Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.
基金This research is supported by the National Natural Science Foundation of China (under Grant No.59771014 and No.50071019). The help of the National Advanced Material Open Research Lab of Tsinghua University is gratefully acknowledged.
文摘The microstructural characteristic of 1070AI matrix composites reinforced by 0.15 祄 AI2O3 particles whose volume fraction was 40% was investigated by TEM and HREM. The results showed that the interface between the matrix and reinforcements was clean and bonded well, without any interfacial reaction products. There were some preferential crystallographic orientation relationships between Al matrix and AI2O3 particle because of the lattice imperfection on the surface of Al2O3 particles.
基金sponsored by Coal and Energy Research Bureau and CDC-NIOSH under Grant No.R01OH009532
文摘Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings.Previous studies showed that the violence of coal specimen failure depends on both the interface friction and width-to-height（W/H） ratio of coal specimen. The mode of failure for a uniaxially loaded coal specimen or a coal pillar is a combination of both shear failure along the interface and compressive failure in the coal. The shear failure along the interface triggered the compressive failure in coal. The compressive failure of a coal specimen or a coal pillar can be controlled by changing its W/H ratio. As the W/H ratio increases, the ultimate strength increases. Hence, with a proper combination of interface friction and the W/H ratio of pillar or coal specimen, the mode of failure will change from sudden violent failure which is brittle failure to non-violent failure which is ductile failure. The main objective of this paper is to determine at what W/H ratio and interface friction the mode of failure changes from violent to non-violent. In this research, coal specimens of W/H ratio ranging from 1 to 10 were uniaxially tested under two interface frictions of 0.1 and 0.25, and the results are presented and discussed.
基金National Natural Science Foundation of China(12072363,12272374,12372373)Special Fund for Fundamental Research of the Central Universities(WK2480000008,WK2480000007,WK2320000049)Anhui Provincial Science and Technology Major Project(202003A05020035)。
文摘Explosion welding was carried out on the basis of vacuum hot melt W/CuCrZr composite plate.Metallurgical microscope,scanning electron microscope and energy dispersive X-ray spectroscope were used to observe the microscopic morphology of the bonding interface.At the same time,combined with finite element calculations,the evolution mechanism of the interface of the hot melt explosion welded W/CuCrZr composite plate was explored.The results show that the interface bonding of the hot melt explosion welded W/CuCrZr composite plate is good and there is a cross-melting zone with 3–8μm in thickness,but cracks are developed on the W side.The numerical simulation reproduces the changes of pressure,stress,strain and internal energy at the bonding interface in the process of hot melt explosion welding.The location of the crack generated in the experiment coincides with the high stress position calculated by numerical simulation.The high pressure and high temperature near the hot melt explosion welding interface further promote the bonding of the interface.
文摘The concept of effective concentration of surfaetant in membrane phase has been proposed,considering the high ad-sorption density of the surfactant at the droplet interfaces in LSM system.The effective concentration of surfactant,C<sub>2</sub>,can be estimated by Eq.（7）—（9）.The swelling caused by emulsification during the initial dispersion process was investigated.The swelling rate wasmeasured by a density method.A model for estimating the"Emulsification" swelling rate,F<sub>se</sub>,has been proposed,basedon a mechanism of swelling due to the entrainment of water resulted from the interracial turbulence and emulsification inthe initial dispersion process.It has been found that Eq.（26）gives excellent fit to the experimental data of Fujinawa,etal.and of the authors.
基金Funded by the National Natural Science Foundation of China (50672089)the Encouraging Foundation for the Scientific Research of the Excellent Young and Middleaged Scientists in Shandong Province(2006BS04034)
文摘The film forming behavior on the interface between air and hydrosol of Fe2O3 nanoparticles was investigated by the surface pressure-time isotherms, the surface pressure-trough area isotherms, Brewster angle microscopy and transmission electron microscopy. It is found that the freshly prepared hydrosol of Fe2O3 nanoparticles is not stable. The surface pressure increases with the aging time and finally approaches a constant, and the smaller the concentration is, the smaller the surface pressure is stabilized at and the shorter the time the hydrosol reaching stable needs. The surface pressure also increases with compression until collapsed, and the longer the hydrosol is aged, the higher the collapsing pressure is. A uniform and compact film composed of nanoparticles with an average diameter of about 2-3 nm on the air-hydrosol interface is observed by Brewster angle microscope and transmission electron microscope.
文摘With increasing usage of a web services today, user required to consecrate reasoning energy to learning the complexities of the interface as opposed to the content. Interface complexity measures the degree of complexity encountered between the user and digital medium like website. This paper presents a New Interface Complexity (NIC) Metric, which partially based on existing schema metrics to weigh human insight of recent service interface;taking into account elements and attributes of XML documents implemented in?World Wide Web Consortium (W3C) XML Schema (WXS) to reduce the structure affecting the effort for comprehending schema documents. The NIC metric is able to draw conclusions about the perceived qualities: interoperability, extensibility and flexibility. It was discovered that there are significant correlations between NIC metric and existing measures. Automating, this practice would be beneficial to developers and designers, as it would help to provide useful feedback in software project design to check the quality of documents for easy maintenance and properly used of XML data for distributed applications.
文摘This paper describes the invesligation of the transfer behaviour of the alkaline earth-metal cations across the water/nitrobenzene interface facilitated by josamycin in the nitrobenzene phase using semi-differential cyclic voltammetry .The peak height is directly proportional to the concentration of josaycin (nb) and to the potential scan rate.The complexes formed from alkaline earth-metal ions and josamycin at the w/nb interface are ML2^2+ ion.
文摘The transfer of Sr^2+ and Ba^2+ ion,facilitated by 18-crown-6 present in the aqueous phase,and of succinylcholine ion at w/nb interface were investigated by semi-differeniial cyclic voltammetry.A good polarographic curve of succinylcholine ion dissolved in water was obtained in the system of 0.01 mol/l LiCl(w)-0.01mol/l TBATPB(nb).The peak current is directly proportional to the concentration of SC^2+ ion.It can be used for the determination of SC and the detection limit is 1.05×10^-5mol/l,The apparent D^m and D^mb have been estimated.The transfer of Sr^2+ and of Ba^2+ at the interface are facilitated by 18-Crown-6 present in the aqueous phase and the peak current is directly proportional to the concentration of 18-Crown-6 in water.This method can be used for the determination of the complexing agent and for the stability constant of the complex formed in the aqueous phase.All the experimental results are in keeping with the theoretical.
