The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray...The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray diffractometer (XRD). All the mineral assemblages are similar in these landslides. The main minerals are montmorillonite, illite, kaolinite, chlorite, quartz and feldspar. There are two kinds of surface microtexture in the slipping zone soil, i.e., linear scratches and arcuate scratches. Based on analyses of the changes of the microtextures, one can obtain information about the number, directions and stages of landslide movements. The authors have also studied the mechanism of landslide formation, evaluated the stability of landslides and revival possibility of ancient landslides and forecasted the activity of similar landslides in different districts. The surface microtexture features of stable landslides and mobile landslides are summarized and it is concluded that the existence of filamentous bacteria may result in or increase movements of landslides.展开更多
Apparent differences in sedimentation and diagenesis exist between carbonate reservoirs in different areas and affect their petrophysical and elastic properties.To elucidate the relevant mechanism,we study and analyze...Apparent differences in sedimentation and diagenesis exist between carbonate reservoirs in different areas and affect their petrophysical and elastic properties.To elucidate the relevant mechanism,we study and analyze the characteristics of rock microstructure and elastic properties of carbonates and their variation regularity using 89 carbonate samples from the different areas The results show that the overall variation regularities of the physical and elastic properties of the carbonate rocks are controlled by the microtextures of the microcrystalline calcite,whereas the traditional classification of rock-and pore-structures is no longer applicable.The micrite microtextures can be divided,with respect to their morphological features,into porous micrite,compact micrite,and tight micrite.As the micrites evolves from the first to the last type,crystal boundaries are observed with increasingly close coalescence,the micritic intercrystalline porosity and pore-throat radius gradually decrease;meanwhile,the rigidity of the calcite microcrystalline particle boundary and elastic homogeneity are enhanced.As a result,the seismic elastic characteristics,such as permeability and velocity of samples,show a general trend of decreasing with the increase of porosity.For low-porosity rock samples(φ<5%)dominated by tight micrite,the micritic pores have limited contributions to porosity and permeability and the micrite elastic properties are similar to those of the rock matrix.In such cases,the macroscopic physical and elastic properties are more susceptible to the formation of cracks and dissolution pores,but these features are controlled by the pore structure.The pore aspect ratio can be used as a good indication of pore types.The bulk modulus aspect ratio for dissolution pores is greater than 0.2,whereas that of the intergranular pores ranges from 0.1 to 0.2.The porous and compact micrites are observed to have a bulk modulus aspect ratio less than 0.1,whereas the ratio of the tight micrite approaches 0.2。展开更多
Microtextures and struetures of 9 hydrothermal chimneys sampled on the small spreading ridge Of the Mari ana Trough during SONNE Cruise 57 (SO57) and 69 (SO69) in 1988 and 1990 were studied by means of scanning elec...Microtextures and struetures of 9 hydrothermal chimneys sampled on the small spreading ridge Of the Mari ana Trough during SONNE Cruise 57 (SO57) and 69 (SO69) in 1988 and 1990 were studied by means of scanning electron microscope. The results reveal that the two types of chimneys from the Mariana Trough. the 'silicic chimneys' containing Fe sulfide and the pure 'silica chimneys' without sulfide, vary distinctly not only in mineral and chemical compositions, but also in microtextures and structures. The silicic chimneys generally show three major types of microtextures.The inside of the chimneys is dominated by holocrystalline or semicrystalline idiomorphic and hypidiomorphic granular textures and the outwall by amorphous colloidal texture. In some of the silicic chimneys relict texture is observed. However,the pure silica chimneys show chiefly amorphous colloidal texture from the inside to the outwall. Microstructurally. theinside of the silicic chimneys is dominated by a 'silica-covering' structure and a 'voidfilling' structure, and the outwall by a chain-like or three-dimentional chain-network structure built up by individual opal globules, whereas the pure silica chimneys are mainly three-dimentional chain-network and the dense silica bands in structure. These variations suggest that not only mineralizing conditions but also processes differ distinctly during the formation of the two types of chimneys, and that hydrothermal mineralization in the Mariana Trough shows a multistage or multieplsodical nature.展开更多
A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,t...A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,the bearing surface of CB using different microtextures,such as wedge-shaped textures(WSTs),square textures(STs),circular textures(CTs),and combined square-circular textures(CSCTs),is simulated and assessed under various external loads of the CB at an engine speed of 2000 r/min.The pressure of the oil film,the frictional force,the force of the solid asperity contact,and the friction coefficient of the CB are used as objective functions.Results indicate that the bearing surface designed by the STs remarkably improves the CB s LFP in comparison with other structures of WSTs,CTs,and CSCTs.Particularly,the average values of the frictional force,solid asperity contact,and friction coefficient of the CB using the STs are greatly reduced by 28.5%,14.5%,and 33.2%and by 34.4%,26.3%,and 43.6%in comparison with the optimized CB dimensions and CTs,respectively.Therefore,the application of the STs on the CB surfaces can enhance the LFP of engines.展开更多
During the metal cutting process,especially in continuous contact conditions like turning,the challenge of lubricants failing to effectively reach the cutting point remains unresolved.Micro-textured cutting tools offe...During the metal cutting process,especially in continuous contact conditions like turning,the challenge of lubricants failing to effectively reach the cutting point remains unresolved.Micro-textured cutting tools offer a potential solution for tool-chip contact challenges.Inspired by the evolutionary achievements of the biosphere,micro-textures are expected to overcome lubrication limitations in cutting zones.Drawing on the anti-gravity water transport seen at the mouth edge of the Nepenthes plant,an innovative microchannel with Nepenthes-shaped contours was designed on the rake face to enable controlled lubricant transport.However,the dynamics of lubricant delivery on textured surfaces are not fully understood.This study first analyzed the microstructure and water transport mechanism of Nepenthes to reconstruct a micro-textured surface for controlled lubricant transport.A dynamic model was then developed to describe lubricant transport within open microchannels,with mathematical simulations predicting transport speed and flow distance.To validate this model,diffusion experiments of alumina soybean oil nanolubricant on polycrystalline diamond(PCD)cutting tool surfaces were conducted,showing an average prediction deviation of 5.01%.Compared with the classical Lucas-Washburn model,the new model improved prediction accuracy by 4.72%.Additionally,comparisons were made to examine droplet spreading and non-uniform diffusion on textured surfaces,revealing that the T2 surface exhibited the strongest unidirectional diffusion characteristics.The contact angle ratio,droplet unidirectional spreading ratio,and droplet spreading aspect ratio were 0.48,1.75,and 3.99,respectively.Finally,the anti-wear,friction-reducing,and efficiency-enhancing mechanisms of micro-textured surfaces in minimum quantity lubrication turning were analyzed.This approach may support continuous cutting of difficult-tomachine materials.展开更多
The world-class Jiaodong gold province in the North China Craton hosts over 5000 t of Au resource and is characterized by abundant visible gold mineralization.However,the critical processes controlling the formation o...The world-class Jiaodong gold province in the North China Craton hosts over 5000 t of Au resource and is characterized by abundant visible gold mineralization.However,the critical processes controlling the formation of visible gold in this province remain poorly understood.To solve this problem,integrated microtextural,trace elemental,and sulfur isotopic analyses of pyrite from the high-grade Linglong gold deposit in the Jiaodong gold province were conducted in this study.Two distinct pyrite types were identified within auriferous quartz-sulfide veins:(1)Py1 aggregates in quartz-pyrite veins(hydrothermal stageⅡ),and(2)euhedral to subhedral,coarse-grained Py2 crystals in quartz-polymetallic sulfide veins(hydrothermal stageⅢ).Microtextural and elemental analyses revealed that visible gold predominantly occurs as intergranular particles between primary pyrite crystals within Py1 aggregates.The Py1 exhibits complex microtextures with abundant mineral inclusions of polymetallic sulfides and has low concentrations of Au(median:0.032 ppm)with a narrowδ^(34)S range(4.86‰-6.75‰),indicative of rapid crystallization under unstable,disequilibrium conditions.By contrast,the Py2 is texturally homogeneous and contains higher Au concentrations(median:0.304 ppm)with progressively increasingδ^(34)S values(5.25‰-10.14‰)over time,suggesting slow crystal growth under more stable,near-equilibrium conditions.Based on the microtextural and geochemical information,it is proposed that fluid boiling occurred only during the hydrothermal stage Ⅱ,which resulted in the unstable physicochemical environment and rapid deposition of gold.During the boiling processes,gold colloids likely occurred and promoted the formation of visible gold.展开更多
The microstructural evolution of banded 5A90 A1-Li alloy during superplastic deformation at 475℃ with an initial strain rate of 8× 10^-4 S^-1 was studied using EBSD technique. The results showed that, before def...The microstructural evolution of banded 5A90 A1-Li alloy during superplastic deformation at 475℃ with an initial strain rate of 8× 10^-4 S^-1 was studied using EBSD technique. The results showed that, before deformation, the grain shape appeared to be banded, the most grain boundaries belonged to low-angle boundaries, and the initial sheet had a dominate of { 110}（112） brass texture. During deformation, there were grain growth, grain shape change, misorientation increasing and textural weakening. The fraction of high-angle boundaries increased rapidly once the flow stress reached the peak value. Corresponding deformation mechanism for various stages of deformation was suggested. Dislocation activity was the dominant mechanism in the first stage, then dynamic recrystallization occurred, and grain rotation was expected as an accommodation for grain boundary sliding （GBS）. At large strains, GBS was the main mechanism.展开更多
Rapid solidification of undercooled Ni-15%Cu （mole fraction） alloy was studied using glass fluxing and cyclic superheating. To show the effect of cooling history on the microstrucyure and microtexture evolution, the...Rapid solidification of undercooled Ni-15%Cu （mole fraction） alloy was studied using glass fluxing and cyclic superheating. To show the effect of cooling history on the microstrucyure and microtexture evolution, the as-solidified samples were either cooled naturally or quenched into water after recalescence. At low undercooling, grain-refined microstructure has a random texture and a highly oriented texture without annealing twins for the case of naturally cooling and quenching, respectively. At high undercooling, a fully random texture as well as a number of annealing twins are observed, and recrystallization and grain growth independently happen on the cooling history. Fluid flow and recrystallization play an important role in the microtexture formation for grain refinement at both low and high undercooling.展开更多
Corrosion re sistance of Zircaloy-4 alloy tube in superheated steam at 673 K/10.3 MPa is anisotropic.A part of the surface undergoes uniform corrosion while the other suffers nodular corrosion.Narrow and wide nodules ...Corrosion re sistance of Zircaloy-4 alloy tube in superheated steam at 673 K/10.3 MPa is anisotropic.A part of the surface undergoes uniform corrosion while the other suffers nodular corrosion.Narrow and wide nodules are observed after an exposure period of 3 and 30 days,respectively.A new matrix transformation method is established in order to study the formation mechanism of nodules in the cross-section(CS) of Zircaloy-4 alloy tube using the EBSD technique,while the CS perpendicular to axial direction(AD).The results reveal that the microtexture is a key factor behind the two types of corrosion.Furthermore,the oxide layers grow anisotropically over the corroded surface.A thick oxide layer forms over the nodular corrosion region on the grains with c-axis oriented in the range of 40° around tangential direction(TD),whereas a thin oxide layer over the uniform corrosion region is detected on the grains with c-axis oriented in the range of 68° around TD.In short,the anisotropic growth of oxide layer was caused by the change of microtexture of the Zr-4 alloy tube,and this anisotropic growth of oxide layer contributed to the nodules formation.展开更多
The Tepearasi Formation of the autochthonous Geyikdagi Group in the CentralTauride Belt, SE of Beysehir, is Dogger in age and consists dominantly of massive limestones andgreyish dolomites occurring within the middle ...The Tepearasi Formation of the autochthonous Geyikdagi Group in the CentralTauride Belt, SE of Beysehir, is Dogger in age and consists dominantly of massive limestones andgreyish dolomites occurring within the middle to upper sections. The total thickness of thedolomitic levels ranges from 100-300 m and laterally extends 500-700 m. Three types of dolomite weredistinguished through petrographic analyses: homogeneous, mottled (saddle-crystalline) andjoint-filling dolomite, which were interpreted to have formed in two different stages, earlydiagenetic and late diagenetic. The homogeneous dolomite of the early diagenetic stage islight-coloured and monotonous-textured and shows the form of a dolosparite mosaic. The mottleddolomite formed in the late diagenetic stage is light- to dark-coloured and coarsely granularidiomorphic. The other type of late diagenetic dolomite, described as the joint-filling type,presents a crystal growth pattern from the joint walls towards the centre of the joint space. It isassociated with coarse calcite crystals as well as primary dolomite crystal clasts which were formedin the early diagenetic stage. In addition to these characteristics, cataclastic texture indicatingthe influence of tectonism is also observed. Microtexture-oriented scanning electron microscopy(SEM) studies indicate that mottled dolomites show zonal structures and contain secondarydissolution vugs. SEM studies also revealed the existence of some remains (calcite, clay etc.) injoint-filling dolomites. Analyses by energy dispersive spectrometry (EDS) indicate the existence ofclay minerals (likely to be illite) in the pores of dolomite. Isotope studies conducted to shedlight onto the origin of the dolomites of the Tepearasi Formation yielded the results of delta^18O=-2.48 to - 3.87 per thousand and delta^13C=0.93 to l.12 per thousand for the early diagenetichomogeneous dolomites. Mottled and joint-filling type dolomites of the late diagenetic stage, on theother hand, gave the results of delta^18O = -5.42 to -7.12 per thousand, and delta^13C= -2.29 and-5.70 respectively. X-Ray diffractometry (XRD) and energy dispersive analysis X-Ray (EDAX), atomicabsorption spectrometry (AAS) analyses, results of petrographic data, and delta^18O and delta^13Cvalues suggest that the early diagenetic dolomitization in the Tepearasi Formation occurred underthe control of hypersaline (rich in Mg) and fresh water mixing zone. The late diagenetic dolomitespartly developed under the control of tectonic thrusting.展开更多
The microstructure and mechanical properties of Inconel 617 alloy rolled at room temperature with different deformation degrees(20%,50%,70%)were investigated.The grain refinement mechanism and main texture types of In...The microstructure and mechanical properties of Inconel 617 alloy rolled at room temperature with different deformation degrees(20%,50%,70%)were investigated.The grain refinement mechanism and main texture types of Inconel 617 alloy during rolling were analyzed via electron backscatter diffraction and X-ray diffraction,and the microhardness and tensile properties of Inconel 617 alloy with different deformation degrees were tested.Results reveal that the grains of Inconel 617 alloy are refined during the rolling deformation process,and the refinement mechanism is the fragmentation of original grains caused by the increase in dislocation density and strain gradient.The main microtextures of the rolled samples are Goss{011}<001>,Rotated Goss{110}<110>,Brass{011}<211>,and P{011}<112>textures,and their intensity is increased with increase in deformation degree.After rolling deformation,the strength of the Inconel 617 alloy is improved and the ductility is reduced by the combined effect of grain refinement and dislocation strengthening.Comprehensively,the yield strength and elongation of Inconel 617 alloy after 20%deformation are 772.48 MPa and 0.1962,respectively,presenting good synergy effect.展开更多
Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions,such as reducing friction,improving wear and increasing wettability.Accurate prediction of micro/nano surface te...Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions,such as reducing friction,improving wear and increasing wettability.Accurate prediction of micro/nano surface textures is of great significance for the design,fabrication and application of functional textured surfaces.In this paper,based on the kinematic analysis of cutter teeth,the discretization of ultrasonic machining process,transformation method of coordinate systems and the cubic spline data interpolation,an integrated theoretical model was established to characterize the distribution and geometric features of micro textures on the surfaces machined by different types of ultrasonic vibration-assisted milling(UVAM).Based on the theoretical model,the effect of key process parameters(vibration directions,vibration dimensions,cutting parameters and vibration parameters)on tool trajectories and microtextured surface morphology in UVAM is investigated.Besides,the effect of phase difference on the elliptical shape in 2D/3D ultrasonic elliptical vibration-assisted milling(UEVAM)was analyzed.Compared to conventional numerical models,the method of the cubic spline data interpolation is applied to the simulation of microtextured surface morphology in UVAM,which is more suitable for characterizing the morphological features of microtextured surfaces than traditional methods due to the presence of numerous micro textures.The prediction of surface roughness indicates that the magnitude of ultrasonic amplitude in z-direction should be strictly limited in 1D rotary UVAM,2D and 3D UEVAM due to the unfavorable effect of axial ultrasonic vibration on the surface quality.This study can provide theoretical guidance for the design and fabrication of microtextured surfaces in UVAM.展开更多
Static recrystallization(SRX)characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080–1170℃ under strain rates of 0.01–0.1 s^(−1),strains of 0.1,0.22,or 0.5,and holding ...Static recrystallization(SRX)characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080–1170℃ under strain rates of 0.01–0.1 s^(−1),strains of 0.1,0.22,or 0.5,and holding time of 0–300 s.The impacts of temperature,strain rate,holding time,and strain on the SRXed grain size,volume fraction,and microtexture were explored by electron backscatter diffraction technique.It was found that temperature played a key role in these processes.As SRX progressed,the<110>fiber parallel to the axis compression direction gradually weakened and was replaced by the<001>fiber because<001>was the preferred recrystallization orientation and grain growth direction for the Ni-based superalloy.Moreover,high temperatures and low strain rates promoted the formation of the<001>fiber.Three nucleation mechanisms during SRX process were found:grain boundary bulging,primary twin assistance,and subgrain coalescence.Grain boundary bulging occurred under all process conditions;however,at low temperatures and high strain rates,the latter two mechanisms could provide additional nucleation modes.In addition,SRX size and volume fraction models were established.展开更多
The paper deals mainly with the relationship between the microtexture types and the indices of physicomechanical properties of loess. The results of study demonstrate that the study of microtextures of loess is of imp...The paper deals mainly with the relationship between the microtexture types and the indices of physicomechanical properties of loess. The results of study demonstrate that the study of microtextures of loess is of importance in the prediction and preliminary evaluation of engineering geological properties of loess in a region.展开更多
文摘The mineral assemblage and content and surface microtextures of slipping zone soil of several landslides in the Three Gorges Reservoir District have been analyzed using the scanning electron microscope (SEM) and X-ray diffractometer (XRD). All the mineral assemblages are similar in these landslides. The main minerals are montmorillonite, illite, kaolinite, chlorite, quartz and feldspar. There are two kinds of surface microtexture in the slipping zone soil, i.e., linear scratches and arcuate scratches. Based on analyses of the changes of the microtextures, one can obtain information about the number, directions and stages of landslide movements. The authors have also studied the mechanism of landslide formation, evaluated the stability of landslides and revival possibility of ancient landslides and forecasted the activity of similar landslides in different districts. The surface microtexture features of stable landslides and mobile landslides are summarized and it is concluded that the existence of filamentous bacteria may result in or increase movements of landslides.
基金supported by the National Natural Science Foundation of China(Nos.41774136 and 41374135)the Sichuan Science and Technology Program(No.2016ZX05004-003)
文摘Apparent differences in sedimentation and diagenesis exist between carbonate reservoirs in different areas and affect their petrophysical and elastic properties.To elucidate the relevant mechanism,we study and analyze the characteristics of rock microstructure and elastic properties of carbonates and their variation regularity using 89 carbonate samples from the different areas The results show that the overall variation regularities of the physical and elastic properties of the carbonate rocks are controlled by the microtextures of the microcrystalline calcite,whereas the traditional classification of rock-and pore-structures is no longer applicable.The micrite microtextures can be divided,with respect to their morphological features,into porous micrite,compact micrite,and tight micrite.As the micrites evolves from the first to the last type,crystal boundaries are observed with increasingly close coalescence,the micritic intercrystalline porosity and pore-throat radius gradually decrease;meanwhile,the rigidity of the calcite microcrystalline particle boundary and elastic homogeneity are enhanced.As a result,the seismic elastic characteristics,such as permeability and velocity of samples,show a general trend of decreasing with the increase of porosity.For low-porosity rock samples(φ<5%)dominated by tight micrite,the micritic pores have limited contributions to porosity and permeability and the micrite elastic properties are similar to those of the rock matrix.In such cases,the macroscopic physical and elastic properties are more susceptible to the formation of cracks and dissolution pores,but these features are controlled by the pore structure.The pore aspect ratio can be used as a good indication of pore types.The bulk modulus aspect ratio for dissolution pores is greater than 0.2,whereas that of the intergranular pores ranges from 0.1 to 0.2.The porous and compact micrites are observed to have a bulk modulus aspect ratio less than 0.1,whereas the ratio of the tight micrite approaches 0.2。
文摘Microtextures and struetures of 9 hydrothermal chimneys sampled on the small spreading ridge Of the Mari ana Trough during SONNE Cruise 57 (SO57) and 69 (SO69) in 1988 and 1990 were studied by means of scanning electron microscope. The results reveal that the two types of chimneys from the Mariana Trough. the 'silicic chimneys' containing Fe sulfide and the pure 'silica chimneys' without sulfide, vary distinctly not only in mineral and chemical compositions, but also in microtextures and structures. The silicic chimneys generally show three major types of microtextures.The inside of the chimneys is dominated by holocrystalline or semicrystalline idiomorphic and hypidiomorphic granular textures and the outwall by amorphous colloidal texture. In some of the silicic chimneys relict texture is observed. However,the pure silica chimneys show chiefly amorphous colloidal texture from the inside to the outwall. Microstructurally. theinside of the silicic chimneys is dominated by a 'silica-covering' structure and a 'voidfilling' structure, and the outwall by a chain-like or three-dimentional chain-network structure built up by individual opal globules, whereas the pure silica chimneys are mainly three-dimentional chain-network and the dense silica bands in structure. These variations suggest that not only mineralizing conditions but also processes differ distinctly during the formation of the two types of chimneys, and that hydrothermal mineralization in the Mariana Trough shows a multistage or multieplsodical nature.
基金The National Key Research and Development Program of China(No.2019YFB2006402)the Open Fund Project of Hubei Key Laboratory of Intelligent Transportation Technology and Device,Hubei Polytechnic University(No.2021XZ107)the Key Scientific Research Project of Hubei Polytechnic University(No.21xjz02A).
文摘A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,the bearing surface of CB using different microtextures,such as wedge-shaped textures(WSTs),square textures(STs),circular textures(CTs),and combined square-circular textures(CSCTs),is simulated and assessed under various external loads of the CB at an engine speed of 2000 r/min.The pressure of the oil film,the frictional force,the force of the solid asperity contact,and the friction coefficient of the CB are used as objective functions.Results indicate that the bearing surface designed by the STs remarkably improves the CB s LFP in comparison with other structures of WSTs,CTs,and CSCTs.Particularly,the average values of the frictional force,solid asperity contact,and friction coefficient of the CB using the STs are greatly reduced by 28.5%,14.5%,and 33.2%and by 34.4%,26.3%,and 43.6%in comparison with the optimized CB dimensions and CTs,respectively.Therefore,the application of the STs on the CB surfaces can enhance the LFP of engines.
基金Supported by National Natural Science Foundation of China(Grant Nos.52375447,52305477 and 52105457)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2023QE057,ZR2024QE100 and ZR2024ME255)+2 种基金Qingdao Municipal Science and Technology Planning Park Cultivation Plan(Grant No.23-1-5-yqpy-17-qy)the Science and Technology SMEs Innovation Capacity Improvement Project of Shandong Province(Grant No.2022TSGC1115)the Special Fund of Taishan Scholars Project。
文摘During the metal cutting process,especially in continuous contact conditions like turning,the challenge of lubricants failing to effectively reach the cutting point remains unresolved.Micro-textured cutting tools offer a potential solution for tool-chip contact challenges.Inspired by the evolutionary achievements of the biosphere,micro-textures are expected to overcome lubrication limitations in cutting zones.Drawing on the anti-gravity water transport seen at the mouth edge of the Nepenthes plant,an innovative microchannel with Nepenthes-shaped contours was designed on the rake face to enable controlled lubricant transport.However,the dynamics of lubricant delivery on textured surfaces are not fully understood.This study first analyzed the microstructure and water transport mechanism of Nepenthes to reconstruct a micro-textured surface for controlled lubricant transport.A dynamic model was then developed to describe lubricant transport within open microchannels,with mathematical simulations predicting transport speed and flow distance.To validate this model,diffusion experiments of alumina soybean oil nanolubricant on polycrystalline diamond(PCD)cutting tool surfaces were conducted,showing an average prediction deviation of 5.01%.Compared with the classical Lucas-Washburn model,the new model improved prediction accuracy by 4.72%.Additionally,comparisons were made to examine droplet spreading and non-uniform diffusion on textured surfaces,revealing that the T2 surface exhibited the strongest unidirectional diffusion characteristics.The contact angle ratio,droplet unidirectional spreading ratio,and droplet spreading aspect ratio were 0.48,1.75,and 3.99,respectively.Finally,the anti-wear,friction-reducing,and efficiency-enhancing mechanisms of micro-textured surfaces in minimum quantity lubrication turning were analyzed.This approach may support continuous cutting of difficult-tomachine materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.42302106 and 42102089)National Foundation for Guiding Local Science and Technology Development(Guizhou[2024]043)Innovation and Development Fund of Science and Technology of Institute of Geochemistry,Chinese Academy of Sciences(Grant No.2025-1).
文摘The world-class Jiaodong gold province in the North China Craton hosts over 5000 t of Au resource and is characterized by abundant visible gold mineralization.However,the critical processes controlling the formation of visible gold in this province remain poorly understood.To solve this problem,integrated microtextural,trace elemental,and sulfur isotopic analyses of pyrite from the high-grade Linglong gold deposit in the Jiaodong gold province were conducted in this study.Two distinct pyrite types were identified within auriferous quartz-sulfide veins:(1)Py1 aggregates in quartz-pyrite veins(hydrothermal stageⅡ),and(2)euhedral to subhedral,coarse-grained Py2 crystals in quartz-polymetallic sulfide veins(hydrothermal stageⅢ).Microtextural and elemental analyses revealed that visible gold predominantly occurs as intergranular particles between primary pyrite crystals within Py1 aggregates.The Py1 exhibits complex microtextures with abundant mineral inclusions of polymetallic sulfides and has low concentrations of Au(median:0.032 ppm)with a narrowδ^(34)S range(4.86‰-6.75‰),indicative of rapid crystallization under unstable,disequilibrium conditions.By contrast,the Py2 is texturally homogeneous and contains higher Au concentrations(median:0.304 ppm)with progressively increasingδ^(34)S values(5.25‰-10.14‰)over time,suggesting slow crystal growth under more stable,near-equilibrium conditions.Based on the microtextural and geochemical information,it is proposed that fluid boiling occurred only during the hydrothermal stage Ⅱ,which resulted in the unstable physicochemical environment and rapid deposition of gold.During the boiling processes,gold colloids likely occurred and promoted the formation of visible gold.
基金Project(51205419)supported by the National Natural Science Foundation of China
文摘The microstructural evolution of banded 5A90 A1-Li alloy during superplastic deformation at 475℃ with an initial strain rate of 8× 10^-4 S^-1 was studied using EBSD technique. The results showed that, before deformation, the grain shape appeared to be banded, the most grain boundaries belonged to low-angle boundaries, and the initial sheet had a dominate of { 110}（112） brass texture. During deformation, there were grain growth, grain shape change, misorientation increasing and textural weakening. The fraction of high-angle boundaries increased rapidly once the flow stress reached the peak value. Corresponding deformation mechanism for various stages of deformation was suggested. Dislocation activity was the dominant mechanism in the first stage, then dynamic recrystallization occurred, and grain rotation was expected as an accommodation for grain boundary sliding （GBS）. At large strains, GBS was the main mechanism.
基金Project(2011CB610403)supported by the National Basic Research Program of ChinaProject(51125002)supported by the National Natural Science Fund for Distinguished Young Scholars of China+3 种基金Projects(51101122,51071127,50901059)supported by the National Natural Science Foundation of ChinaProject(1110502)supported by the Fok Ying Tong Education Foundation,ChinaProjects(66-QP-2010,24-TZ-2009)supported by the Free Research Fund of State Key Laboratory of Solidification Processing,ChinaProject(B08040)supported by the Program of Introducing Talents of Discipline to Universities,China
文摘Rapid solidification of undercooled Ni-15%Cu （mole fraction） alloy was studied using glass fluxing and cyclic superheating. To show the effect of cooling history on the microstrucyure and microtexture evolution, the as-solidified samples were either cooled naturally or quenched into water after recalescence. At low undercooling, grain-refined microstructure has a random texture and a highly oriented texture without annealing twins for the case of naturally cooling and quenching, respectively. At high undercooling, a fully random texture as well as a number of annealing twins are observed, and recrystallization and grain growth independently happen on the cooling history. Fluid flow and recrystallization play an important role in the microtexture formation for grain refinement at both low and high undercooling.
文摘Corrosion re sistance of Zircaloy-4 alloy tube in superheated steam at 673 K/10.3 MPa is anisotropic.A part of the surface undergoes uniform corrosion while the other suffers nodular corrosion.Narrow and wide nodules are observed after an exposure period of 3 and 30 days,respectively.A new matrix transformation method is established in order to study the formation mechanism of nodules in the cross-section(CS) of Zircaloy-4 alloy tube using the EBSD technique,while the CS perpendicular to axial direction(AD).The results reveal that the microtexture is a key factor behind the two types of corrosion.Furthermore,the oxide layers grow anisotropically over the corroded surface.A thick oxide layer forms over the nodular corrosion region on the grains with c-axis oriented in the range of 40° around tangential direction(TD),whereas a thin oxide layer over the uniform corrosion region is detected on the grains with c-axis oriented in the range of 68° around TD.In short,the anisotropic growth of oxide layer was caused by the change of microtexture of the Zr-4 alloy tube,and this anisotropic growth of oxide layer contributed to the nodules formation.
文摘The Tepearasi Formation of the autochthonous Geyikdagi Group in the CentralTauride Belt, SE of Beysehir, is Dogger in age and consists dominantly of massive limestones andgreyish dolomites occurring within the middle to upper sections. The total thickness of thedolomitic levels ranges from 100-300 m and laterally extends 500-700 m. Three types of dolomite weredistinguished through petrographic analyses: homogeneous, mottled (saddle-crystalline) andjoint-filling dolomite, which were interpreted to have formed in two different stages, earlydiagenetic and late diagenetic. The homogeneous dolomite of the early diagenetic stage islight-coloured and monotonous-textured and shows the form of a dolosparite mosaic. The mottleddolomite formed in the late diagenetic stage is light- to dark-coloured and coarsely granularidiomorphic. The other type of late diagenetic dolomite, described as the joint-filling type,presents a crystal growth pattern from the joint walls towards the centre of the joint space. It isassociated with coarse calcite crystals as well as primary dolomite crystal clasts which were formedin the early diagenetic stage. In addition to these characteristics, cataclastic texture indicatingthe influence of tectonism is also observed. Microtexture-oriented scanning electron microscopy(SEM) studies indicate that mottled dolomites show zonal structures and contain secondarydissolution vugs. SEM studies also revealed the existence of some remains (calcite, clay etc.) injoint-filling dolomites. Analyses by energy dispersive spectrometry (EDS) indicate the existence ofclay minerals (likely to be illite) in the pores of dolomite. Isotope studies conducted to shedlight onto the origin of the dolomites of the Tepearasi Formation yielded the results of delta^18O=-2.48 to - 3.87 per thousand and delta^13C=0.93 to l.12 per thousand for the early diagenetichomogeneous dolomites. Mottled and joint-filling type dolomites of the late diagenetic stage, on theother hand, gave the results of delta^18O = -5.42 to -7.12 per thousand, and delta^13C= -2.29 and-5.70 respectively. X-Ray diffractometry (XRD) and energy dispersive analysis X-Ray (EDAX), atomicabsorption spectrometry (AAS) analyses, results of petrographic data, and delta^18O and delta^13Cvalues suggest that the early diagenetic dolomitization in the Tepearasi Formation occurred underthe control of hypersaline (rich in Mg) and fresh water mixing zone. The late diagenetic dolomitespartly developed under the control of tectonic thrusting.
基金Natural Science Foundation of Gansu Province(23JRRA922)National Natural Science Foundation of China(52265049)+1 种基金Industrial Support Program for Colleges and Universities in Gansu Province(2022CYZC-26)Key Research and Development Plan Project of Gansu Province(23YFGA0054)。
文摘The microstructure and mechanical properties of Inconel 617 alloy rolled at room temperature with different deformation degrees(20%,50%,70%)were investigated.The grain refinement mechanism and main texture types of Inconel 617 alloy during rolling were analyzed via electron backscatter diffraction and X-ray diffraction,and the microhardness and tensile properties of Inconel 617 alloy with different deformation degrees were tested.Results reveal that the grains of Inconel 617 alloy are refined during the rolling deformation process,and the refinement mechanism is the fragmentation of original grains caused by the increase in dislocation density and strain gradient.The main microtextures of the rolled samples are Goss{011}<001>,Rotated Goss{110}<110>,Brass{011}<211>,and P{011}<112>textures,and their intensity is increased with increase in deformation degree.After rolling deformation,the strength of the Inconel 617 alloy is improved and the ductility is reduced by the combined effect of grain refinement and dislocation strengthening.Comprehensively,the yield strength and elongation of Inconel 617 alloy after 20%deformation are 772.48 MPa and 0.1962,respectively,presenting good synergy effect.
基金Supported by Shandong Provincial Natural Science Foundation of China(Grant No.ZR2023QE041)China Postdoctoral Science Foundation(Grant No.2023M731862)National Natural Science Foundation of China(Grant No.51975112).
文摘Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions,such as reducing friction,improving wear and increasing wettability.Accurate prediction of micro/nano surface textures is of great significance for the design,fabrication and application of functional textured surfaces.In this paper,based on the kinematic analysis of cutter teeth,the discretization of ultrasonic machining process,transformation method of coordinate systems and the cubic spline data interpolation,an integrated theoretical model was established to characterize the distribution and geometric features of micro textures on the surfaces machined by different types of ultrasonic vibration-assisted milling(UVAM).Based on the theoretical model,the effect of key process parameters(vibration directions,vibration dimensions,cutting parameters and vibration parameters)on tool trajectories and microtextured surface morphology in UVAM is investigated.Besides,the effect of phase difference on the elliptical shape in 2D/3D ultrasonic elliptical vibration-assisted milling(UEVAM)was analyzed.Compared to conventional numerical models,the method of the cubic spline data interpolation is applied to the simulation of microtextured surface morphology in UVAM,which is more suitable for characterizing the morphological features of microtextured surfaces than traditional methods due to the presence of numerous micro textures.The prediction of surface roughness indicates that the magnitude of ultrasonic amplitude in z-direction should be strictly limited in 1D rotary UVAM,2D and 3D UEVAM due to the unfavorable effect of axial ultrasonic vibration on the surface quality.This study can provide theoretical guidance for the design and fabrication of microtextured surfaces in UVAM.
基金supported by the technology development fund of Beijing Research Institute of Mechanical&Electrical Technology Co.,Ltd.,CAM,Construction of Innovation Leading Talents and Innovation Team of China Academy of Machinery Science and Technology Group:Vacuum forming technology and equipment innovation team.
文摘Static recrystallization(SRX)characteristics of a powder metallurgy superalloy were investigated by isothermal compression at 1080–1170℃ under strain rates of 0.01–0.1 s^(−1),strains of 0.1,0.22,or 0.5,and holding time of 0–300 s.The impacts of temperature,strain rate,holding time,and strain on the SRXed grain size,volume fraction,and microtexture were explored by electron backscatter diffraction technique.It was found that temperature played a key role in these processes.As SRX progressed,the<110>fiber parallel to the axis compression direction gradually weakened and was replaced by the<001>fiber because<001>was the preferred recrystallization orientation and grain growth direction for the Ni-based superalloy.Moreover,high temperatures and low strain rates promoted the formation of the<001>fiber.Three nucleation mechanisms during SRX process were found:grain boundary bulging,primary twin assistance,and subgrain coalescence.Grain boundary bulging occurred under all process conditions;however,at low temperatures and high strain rates,the latter two mechanisms could provide additional nucleation modes.In addition,SRX size and volume fraction models were established.
文摘The paper deals mainly with the relationship between the microtexture types and the indices of physicomechanical properties of loess. The results of study demonstrate that the study of microtextures of loess is of importance in the prediction and preliminary evaluation of engineering geological properties of loess in a region.
