Utilizing phosphorus tailings as the raw material for foam concrete is a key approach to achieving sustainable and efficient resource utilization.During the preparation of phosphorus tailings-based foam concrete,slurr...Utilizing phosphorus tailings as the raw material for foam concrete is a key approach to achieving sustainable and efficient resource utilization.During the preparation of phosphorus tailings-based foam concrete,slurry performance is critical to the successful production.Phosphorus tailings,cement and microsilica were used to prepare foam concrete slurry in this study.A rheometer was employed as a test tool to measure the variation of linear viscoelastic zone(LVR),viscosity,and yield stress of the slurries with different cement contents.The results indicate that the phosphorus tailings-cement-microsilica slurry exhibits shear-thinning properties,which aligns well with the Herschel-Bulkley model,showing a high degree of correlation.As the cement content increases,the energy storage modulus of the slurry rises,and the LVR length shows a nonlinear trend.The LVR reaches its maximum length of 0.04%when the cement content is 6 mass%or 8 mass%.The increment of the cement content leads to a more intricate internal network structure,which hinders the reconstruction rate of the flocculated structure after high-shear deformation.展开更多
In this work,the influences of surface layer slurry at different temperatures(10℃,14℃,18℃,22℃)on wax patterns deformation,shrinkage,slurry coating characteristics,and the surface quality of the casting were invest...In this work,the influences of surface layer slurry at different temperatures(10℃,14℃,18℃,22℃)on wax patterns deformation,shrinkage,slurry coating characteristics,and the surface quality of the casting were investigated by using a single factor variable method.The surface morphologies of the shell molds produced by different temperatures of the surface(first)layer slurries were observed via electron microscopy.Furthermore,the microscopic composition of these shell molds was obtained by EDS,and the osmotic effect of the slurry on the wax patterns at different temperatures was also assessed by the PZ-200 Contact Angle detector.The forming reasons for the surface cracks and holes of thick and large ZTC4 titanium alloy by investment casting were analyzed.The experimental results show that the surface of the shell molds prepared by the surface layer slurry with a low temperature exhibits noticeable damage,which is mainly due to the poor coating performance and the serious expansion and contraction of wax pattern at low temperatures.The second layer shell material(SiO_(2),Al_(2)O_(3))immerses into the crack area of the surface layer,contacts and reacts with the molten titanium to form surface cracks and holes in the castings.With the increase of the temperature of surface layer slurry,the damage to the shell surface tends to weaken,and the composition of the shell molds'surface becomes more uniform with less impurities.The results show that the surface layer slurry at 22℃is evenly coated on the surface of the wax patterns with appropriate thickness,and there is no surface shell mold rupture caused by sliding slurry after sand leaching.The surface layer slurry temperature is consistent with the wax pattern temperature and the workshop temperature,so there is no damage of the surface layer shell caused by expansion and contraction.Therefore,the shell mold prepared by the surface layer slurry at this temperature has good integrity,isolating the contact between the low inert shell material and the titanium liquid effectively,and the ZTC4 titanium alloy cylinder casting prepared by this shell mold is smooth,without cracks and holes.展开更多
The multipath application of green resources needs to be realised under the carbon neutrality goal.Worldwide,biomass is a resource in urgent need of treatment.In this paper,corn stover biomass(YM)or biochar with diffe...The multipath application of green resources needs to be realised under the carbon neutrality goal.Worldwide,biomass is a resource in urgent need of treatment.In this paper,corn stover biomass(YM)or biochar with different particle sizes(YMF or YMX)was added during the preparation of coal-water slurry to investigate its effect on the performance of coal-water slurry and the micro-mechanism.The results showed that the fixed viscosity concentration of coal-water slurry(CYWS)with YM was only 47.42%,and the flowability was 49.9 mm,which made the slurry performance poor.The fixed viscosity concentration of coal-water slurry(CFWS)blended with YMF and coal-water slurry(CXWS)blended with YMX increased by 10.41%and 14.24%,respectively,compared with CYWS.Meanwhile,CXWS had the lowest thixotropy and yield stress,with a yield stress of only 16.13 Pa,which was 77.31 Pa lower than that of CYWS.This indicates that YMX treated by charring and milling is more favorable to be blended with coal to prepare coal-water slurry.This is due to the enhanced hydrophilicity and electronegativity of YMX.The enhanced hydrophilicity reduces the tendency to form three-dimensional networks in coal-water slurry,while the enhanced electronegativity improves the electrostatic repulsion between particles,which is beneficial to the dispersion of particles.In the subsequent EDLVO analyses,the same idea was proved.展开更多
Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosph...Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosphogypsum.However,pipe plugging,which is caused by the poor workability of HPG-based filling materials,has become a major safety hazard in the filling process.Determining an economical and practicable method is urgently needed to improve the workability of HPG slurry work.First,this work found that grind-ing treatment was much more effective than increasing concentration(59wt%-65wt%)and adding tailings(20wt%-100wt%)in enhan-cing the workability of HPG slurry based on a comprehensive analysis of water retention,fluidity,and flow stability.Then,the combined effects of particle size,particle morphology,water film,and interparticle interactions on the workability of HPG slurry were quantitat-ively described through a microanalysis.Moreover,the first direct evidence for the transformation from robust embedded structures to soft stacking structures was presented.In practice,the filling materials should be prepared by grinding HPG for 20 min and mixing with 0-200wt%phosphorus tailings to achieve satisfactory workability and mechanical performance.The results of this study provide practic-al and feasible methods for addressing the stable transportation problem of HPG slurry.展开更多
Nitrous oxide(N_(2)O)emissions pose a serious environmental problem when nitrogen(N)fertilizer is excessively applied to plantation systems to enhance tree growth.Although biochar can improve soil fertility and mitiga...Nitrous oxide(N_(2)O)emissions pose a serious environmental problem when nitrogen(N)fertilizer is excessively applied to plantation systems to enhance tree growth.Although biochar can improve soil fertility and mitigate soil N losses,our understanding of its interaction with N fertilizer and its long-term effects remains limited owing to experimental constraints.In this study,two microcosm incubation experiments were performed to evaluate the effect of fresh biochar,compared to 8-year field-aged biochar application in a poplar plantation,on soil N_(2)O emissions triggered by biogas slurry application.The experiments incorporated three biochar levels and four biogas slurry application rates,each with three replicates.The results demonstrated that fresh and aged biochar significantly reduced soil cumulative N_(2)O emissions by 31%–61%and 75%–99%,respectively,over 7 d following biogas slurry application.However,these mitigating effects diminished over incubation time.The application of fresh biochar significantly reduced soil available organic carbon and potential denitrification rates,suggesting that it primarily suppressed soil N_(2)O emissions by limiting the supply of electron donors.In contrast,aged biochar had minimal impact on soil available organic carbon and generally enhanced the abundances of bacterial amoA,nirS,nirK,and nosZ genes.This suggests that the aged biochar potentially suppressed soil N_(2)O emissions by promoting complete denitrification.Partial least squares structure equation model(PLS-SEM)analysis corroborated the two different mechanisms regulating the inhibitory influence of fresh and aged biochar on soil N_(2)O emissions.The lower R^(2)of PLS-SEM analysis for aged biochar(R^(2)=0.256)compared to that for fresh biochar(R^(2)=0.798)indicates that other factors,such as biochar properties,potentially affect soil N_(2)O emissions and warrant further investigation.This study highlights the need to evaluate the long-term effect of biochar on soil N_(2)O emissions,owing to the dynamic changes in biochar and soil properties over time.展开更多
Traditional pyrometallurgical and hydrometallurgical methods to extract bismuth from sulfide ores face problems such as high cost,low-concentration SO_(2)generation,and long process time.In this study,the cyclone tech...Traditional pyrometallurgical and hydrometallurgical methods to extract bismuth from sulfide ores face problems such as high cost,low-concentration SO_(2)generation,and long process time.In this study,the cyclone technology and slurry electrolysis method were combined.The bismuth sulfide ore was dissolved directly at the anode,while the high purity bismuth was deposited efficiently at the cathode under the advantages of the two methods.The short process and high-efficiency extraction of bismuth sulfide ore were realized,and the pollution of low-concentration SO_(2)was avoided.Then,the effects of several crucial experimental conditions(current density,reaction time,temperature,pH,liquid-solid ratio,and circulation flow rate)on the leaching efficiency and recovery efficiency of bismuth were investigated.The leaching and electrowinning mechanisms during the recovery process were also analyzed according to the research results of this paper to better understand the cyclone slurry electrolysis process.The experimental results showed that 95.19%bismuth was leached into the acid solution in the anode area under optimal conditions,and the recovery efficiency and purity of bismuth on the cathode reached 91.13%and 99.26%,respectively,which were better than those by the traditional hydrometallurgy recovery process.展开更多
Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with...Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.展开更多
Erosion in slurry pumps presents a persistent challenge in industrial applications.This study examines the erosion of the static components of a 150ZJ-C42 centrifugal slurry pump,currently in operation at a beneficiat...Erosion in slurry pumps presents a persistent challenge in industrial applications.This study examines the erosion of the static components of a 150ZJ-C42 centrifugal slurry pump,currently in operation at a beneficiation plant,under varying particle conditions.Utilizing high-precision three-dimensional reverse engineering,the pump’s flow passage geometry was reconstructed to facilitate detailed erosion analysis.Focusing on the front and rear baffles of the pump chamber,as well as the volute,erosion patterns were analyzed for different particle volume concentrations and sizes.The results reveal that the highest erosion damage consistently occurs near the volute tongue,with wear being most severe in regions adjacent to the partition plate near the rear cover.Erosion damage intensity in this area correlates positively with particle diameter.Notably,the average erosion rate in the volute surpasses that of the front and rear chamber liners,reaching a value as high as 6.03×10^(-7)kg·m^(-2)·s^(-1)at a particle concentration of 9%and diameter of 0.1 mm,adversely impacting pump stability.For the pump chamber baffles,increased erosion is observed at a particle diameter of 0.05 mm under constant volume concentration conditions,while higher particle concentrations exacerbate localized erosion.展开更多
To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Un...To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Undersea Tunnel.To evaluate the discharging performance of short screw conveyor in different cases,the full-scale transient slurry-rock two-phase model for a short screw conveyor actively discharging rocks was established using computational fluid dynamics-discrete element method(CFD-DEM)coupling approach.In the fluid domain of coupling model,the sliding mesh technology was utilized to describe the rotations of the atmospheric composite cutterhead and the short screw conveyor.In the particle domain of coupling model,the dynamic particle factories were established to produce rock particles with the rotation of the cutterhead.And the accuracy and reliability of the CFD-DEM simulation results were validated via the field test and model test.Furthermore,a comprehensive parameter analysis was conducted to examine the effects of TBM operating parameters,the geometric design of screw conveyor and the size of rocks on the discharging performance of short screw conveyor.Accordingly,a reasonable rotational speed of screw conveyor was suggested and applied to Jiaozhou Bay Second Undersea Tunnel project.The findings in this paper could provide valuable references for addressing the excavation chamber clogging during ultra-large-diameter slurry TBM tunneling in hard rock for similar future.展开更多
The influences of reaction temperature,duration,pressure,and catalyst concentration on the molecular transformation of residual slurry phase hydrocracking process were investigated.The molecular composition of the het...The influences of reaction temperature,duration,pressure,and catalyst concentration on the molecular transformation of residual slurry phase hydrocracking process were investigated.The molecular composition of the heteroatom compounds in the residue feedstock and its upgrading products were characterized using high-resolution Orbitrap mass spectrometry coupled with multiple ionization methods.The simultaneous promotion of cracking and hydrogenation reactions was observed with increasing of the reaction temperature and time.Specifically,there was a significant increase in the cracking degree of alkyl side chain,while the removal of low-condensation sulfur compounds such as sulfides and benzothiophenes was enhanced.In particular,the cracking reactions were more significantly facilitated by high temperatures,while an appropriately extended reaction time can result in the complete elimination of the aforementioned sulfur compounds with a lower degree of condensation.Under conditions of low hydrogen pressure and catalyst concentration,the products still exhibit a high relative abundance of easily convertible compounds such as sulfoxides,indicating a significant deficiency in the effectiveness of hydrogenation.The hydrogen pressure exhibits an optimal value,beyond which further increments have no effect on the composition and performance of the liquid product but can increase the yield of the liquid product.At significantly high catalyst concentration,the effect of desulfurization and deoxidation slightly diminishes,while the aromatic saturation of highly condensed compounds was notably enhanced.This hydrogenation saturation effect cannot be attained through manipulation of other operational parameters,thereby potentially benefiting subsequent product processing and utilization.This present study demonstrates a profound comprehension of the molecular-level residue slurry phase hydrocracking process,offering not only specific guide for process design and optimization but also valuable fundamental data for constructing reaction models at the molecular level.展开更多
Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water conten...Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water content and mud water separation rate was established to achieve efficient resource utilization,and the feasibility of foam lightweight soil(FLS)prepared from BT was investigated.The effects of industrial waste residues(fly ash and slag powder)on the properties of FLS were studied.Meanwhile,the micro-mechanisms were revealed by XRD,SEM-EDS,and TG-DSC.The results revealed that fly ash reduced the workability and compressive strength of FLS.Slag powder can significantly enhance the compressive strength of FLS,which increased by 18.60%-23.26%,17.07%-58.54% and 12.12%-52.12%,respectively.Besides,slag powder can improve the long-term water stability performance and enhance carbonation resistance.XRD and thermal analyses showed that adding fly ash decreased the hydration degree of FLS,leading to a decrease in the hydration products.Slag powder improved the pore structure and compacted the skeleton structure of FLS.This study would provide an effective way to realize the resource utilization of BT,fly ash,and slag powder,with certain socio-economic and environmental benefits.展开更多
Shallow-buried thick sand strata present considerable local instability risks during diaphragm wall trenching construction.However,this critical issue has not been extensively studied,despite its serious safety conseq...Shallow-buried thick sand strata present considerable local instability risks during diaphragm wall trenching construction.However,this critical issue has not been extensively studied,despite its serious safety consequences.This paper proposes an automatic identification model for shallow-buried thick sand strata,integrating three-dimensional limit equilibrium theory with a genetic algorithm to precisely identify the most potentially dangerous local instability mass and determine its minimum safety factor.The model establishes three undetermined parameters:failure angle,upper boundary,and thickness of the local instability mass.These parameters define the search space for the local instability mass.The effectiveness of this approach was confirmed through a diaphragm wall engineering case near the Rhine River in France,where the predicted instability location closely aligned with field observations.A systematic analysis of the model indicated that the difference in slurry-groundwater levels and the friction angle are the most significant factors affecting local instability in shallow-buried thick sand strata.The model indicated that the location of the most potentially dangerous instability mass changes depending on geological conditions,and larger instability masses do not always relate to lower safety factors.Additionally,exploratory experiments revealed that support pressure losses caused by slurry infiltration significantly influence local instability calculations in sand strata.This points out the importance of considering these support pressure losses in the stability evaluations of high permeable sand strata.The results improve the evaluation of safety and the optimization of design for diaphragm wall construction in shallow-buried thick sand strata.展开更多
We demonstrate for the first time the critical influence of binder molecular weight on the performance of slurry-cast lithium nickel manganese cobalt oxide(NMC)cathodes in sulfide-based all-solid-state batteries(SSBs)...We demonstrate for the first time the critical influence of binder molecular weight on the performance of slurry-cast lithium nickel manganese cobalt oxide(NMC)cathodes in sulfide-based all-solid-state batteries(SSBs).SSBs are increasingly recognized as a safer and potentially more efficient alternative to traditional Li-ion batteries,owing to the superior ionic conductivities and inherent safety features of sulfide solid electrolytes.However,the integration of high-voltage NMC cathodes with sheet-type sulfide solid electrolytes presents significant fabrication challenges.Our findings reveal that higher molecular weight binders not only enhance the discharge capacity and cycle life of these cathodes but also ensure robust adhesion and structural integrity.By optimizing binder molecular weights,we effectively shield the active materials from degradation and mechanical stress,significantly boosting the functionality and longevity of SSBs.These results underscore the paramount importance of binder properties in advancing the practical application of high-performance all-solid-state batteries.展开更多
Due to the invisibility and complexity of the underground spaces,monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging,which co...Due to the invisibility and complexity of the underground spaces,monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging,which complicates engineering treatment.This research investigated the propagation law of cement-sodium silicate slurry under flowing water conditions within the caving mass of a metal mine.First,based on borehole packer test results and borehole TV images,the fractured strata before grouting were classified into four types:cavity,hidden,fissure,and complete.Second,an orthogonal experimental design was employed to evaluate the impact of four key factors—stratigraphic fragmentation,water flow rate,grouting flow rate,and water-cement ratio—on the efficacy of grouting within a caving mass at the site.The results indicate that the factors influencing grouting efficacy are ranked in the following order of importance:stratigraphic fragmentation>water flow rate>water–cement ratio>grouting flow rate.Ultimately,five propagation filling modes—pure slurry,big crack,small crack,small karst pore,and pore penetration—were identified by examining the propagation filling characteristics of slurry in rock samples,incorporating microscopic material structure analysis through scanning electron microscopy and energy spectrum analysis.The findings of this study provide valuable insights into selecting engineering treatment parameters and methodologies,serving as a reference for preventing and controlling water–sand mixture inrush in metal mines,thereby enhancing treatment efficacy and ensuring grouting success.展开更多
The lanthanum-cerium-based slurry(LC-slurry)is extensively utilized in the chemical mechanical polishing(CMP)of TFT-LCD glass substrates,optical lenses,and other glass products.Sodium hexametaphosphate(SHMP),as a disp...The lanthanum-cerium-based slurry(LC-slurry)is extensively utilized in the chemical mechanical polishing(CMP)of TFT-LCD glass substrates,optical lenses,and other glass products.Sodium hexametaphosphate(SHMP),as a dispersant,is commonly employed to enhance the dispersion properties of LCslurry for improved polishing performance.However,the tendency of sedimentation to form a compacted sediment layer,which is challenging to redisperse,increases storage difficulty and polishing equipment failure risk,thereby limiting its utilization in CMP.In the present study,sodium carboxymethylcellulose(CMC-Na),a long-chain organic polymer,was employed to enhance the redispersibility of LC-slurry containing SHMP.A comprehensive investigation was conducted on the influence of CMC-Na dosage and slurry pH on dispersibility,redispersibility and polishing performance.Additionally,an analysis was carried out to elucidate the underlying mechanism behind the effect of CMC-Na.The study demonstrates that the LC-slurry,containing 250 ppm SHMP and 500 ppm CMC-Na,exhibits excellent dispersibility and redispersibility.Further polishing tests demonstrate that compared to the LC-slurry containing only SHMP,utilizing the slurry containing both SHMP and CMC-Na at various pH for polishing thin film transistor liquid crystal display(TFT-LCD)glass substrates results in a reduction of both material removal rate(MRR)and surface roughness(Sa).Specifically,when adjusting the slurry to a pH range of 5-6,the MRR can reach up to 330 nm/min,which closely approximates the MRR achieved by LC-slurry containing only 250 ppm SHMP at corresponding pH values.Meanwhile,after polishing,the surface roughness of the glass substrate measures approximately 0.47 nm.展开更多
Dairy cattle slurry is a source of nitrogen(N)that can substitute for synthetic fertilizers.This study aimed to identify combinations of synthetic fertilizers and slurry optimal for maize growth and N dynamics in Nort...Dairy cattle slurry is a source of nitrogen(N)that can substitute for synthetic fertilizers.This study aimed to identify combinations of synthetic fertilizers and slurry optimal for maize growth and N dynamics in Northeast China.In a two-year field experiment testing synthetic-to-slurry N fertilization ratios,slurry application increased grain yield and yield components,net economic benefit,and N use efficiency relative to synthetic fertilization but led to higher nitrous oxide and ammonia emissions.A 1:1-1:3 synthetic N:slurry N ratio and slurry application at 60-90 t ha^(-1)balanced productivity with N losses.展开更多
The mathematical model between laser cladding parameters and coating properties was established by the response surface method(RSM).Ni–WC-reinforced CoCrNiFeAl high-entropy alloy(HEA)composite coatings were prepared ...The mathematical model between laser cladding parameters and coating properties was established by the response surface method(RSM).Ni–WC-reinforced CoCrNiFeAl high-entropy alloy(HEA)composite coatings were prepared on the surface of 0Cr13Ni5Mo steel by laser cladding to study the addition of Ni–WC on slurry erosion resistance of coatings.The optimal parameters obtained by RSM are laser power of 1450 W,scanning speed of 4.3 mm/s,powder feeding speed of 1.3 r/min and overlap rate of 60%,respectively.The grains of CoCrNiFeAl composite coatings are refined by adding Ni–WC-reinforced powder.15 wt.%Ni–WC composite coating presents the maximum microhardness with the value of 655 HV_(0.3).The cumulative mass loss of the composite coatings at different erosion angles is lower than that of the pure CoCrNiFeAl coating.In addition,at low erosion angles,the cumulative mass loss of the composite coatings gradually decreases with the increase in the mass fraction of Ni–WC.Ploughing and microcutting are the primary erosion mechanisms of CoCrNiFeAl composite coatings at low erosion angles.When erosion damage occurs at high erosion angle,the erosion mechanisms of composite coating material loss are dominated by lip formation and craters.The proposed high-entropy alloy composite coatings can be applied to improve the erosion resistance of components in contact with high-speed fluids,such as ship propellers and centrifugal pump blades.展开更多
Reef limestone is buried in the continental shelf and marine environment.Understanding the mechanisms governing filter cake formation in coral reef limestone strata is essential for various engineering activities in c...Reef limestone is buried in the continental shelf and marine environment.Understanding the mechanisms governing filter cake formation in coral reef limestone strata is essential for various engineering activities in coastal areas,including slurry pressure balanced(SPB)shield tunneling,which are currently not well understood.This study systematically investigates the slurry infiltration characteristics of different coral reef limestone types with inherent anisotropy,identified by growth line orientations,through a series of micro-infiltration column tests.Multiple slurry concentrations and pressures were used to analyze their effects on slurry infiltration dynamics and filter cake formation.Pre-and post-infiltration CT scanning was conducted to examine skeletal morphology and reconstruct the pore network structure of coral reef limestone samples.The results show that while increased slurry concentrations and pressures generally improve filter cake formation,excessive pressure can compromise filter cake integrity.By employing Dijkstra’s algorithm in a pore network model,the study identified primary seepage pathways,highlighting the significant role of near-vertical throat clusters in the infiltration process.A comprehensive analysis of pore structure and connectivity indices before and after infiltration revealed that the orientation of growth lines in coral reef limestone is the primary factor influencing macroscopic slurry infiltration behavior.These findings offer valuable insights for the design and execution of tunneling projects through coral reef limestone formations,especially in coastal regions.展开更多
We examined the mechanical strength and microscopic property effects of bottom ash(BA)recycled concrete made by partially substituting natural aggregates made from three industrial wastes,fly ash(FA),silica fume(SF),f...We examined the mechanical strength and microscopic property effects of bottom ash(BA)recycled concrete made by partially substituting natural aggregates made from three industrial wastes,fly ash(FA),silica fume(SF),furnace slag(FS),and cement after BA was treated with slurry to improve the properties of BA and increase its utilisation.The compressive,flexural,splitting tensile strengths,and drying shrinkage test of the recycled concrete from BA were tested at the macroscopic level,and the specimens were analyzed by scanning electron microscopy(SEM)at the microscopic level.The experimental results show that the slurry treatment of BA results in a corresponding improvement in the macroscopic and microscopic properties of the obtained slurry-bound BA aggregates.The synergistic effect of FA and SF can better fill the pores on the surface of BA,which in turn can better improve the properties of recycled concrete.This study provides a theoretical support for improving the properties of BA and promoting its utilisation as a resource.展开更多
In this paper is presented a concept solution and acceptance test application procedure of deep pit protection structure,intended for three underground levels of residential building:A,B,C,D,block 10C,Budva,Montenegro...In this paper is presented a concept solution and acceptance test application procedure of deep pit protection structure,intended for three underground levels of residential building:A,B,C,D,block 10C,Budva,Montenegro.The anchored wall used consist of nongravity cantilevered walls with three levels of ground anchors.Nongravity cantilevered walls employ continuous walls constructed in slurry trenches(i.e.,slurry(diaphragm)walls),e.g vertical elements that are drilled to depths below the finished excavation grade.For those nongravity cantilevered walls,support is provided through the shear and bending stiffness of the vertical wall elements and passive resistance from the soil below the finished excavation grade.Anchored wall support relies on these components as well as lateral resistance provided by the ground anchors to resist horizontal pressures(e.g.,earth,water,external loads)acting on the wall.Anchored wall analysed and applied is temporary supporting structure necessary for the excavation and erection of the underground structure part up to ground surface level.Temporary ground anchors lifetime is up to two years.Dynamic loads are not considered.展开更多
基金Hubei Provincial Key Research Program Project(2023BCB099).
文摘Utilizing phosphorus tailings as the raw material for foam concrete is a key approach to achieving sustainable and efficient resource utilization.During the preparation of phosphorus tailings-based foam concrete,slurry performance is critical to the successful production.Phosphorus tailings,cement and microsilica were used to prepare foam concrete slurry in this study.A rheometer was employed as a test tool to measure the variation of linear viscoelastic zone(LVR),viscosity,and yield stress of the slurries with different cement contents.The results indicate that the phosphorus tailings-cement-microsilica slurry exhibits shear-thinning properties,which aligns well with the Herschel-Bulkley model,showing a high degree of correlation.As the cement content increases,the energy storage modulus of the slurry rises,and the LVR length shows a nonlinear trend.The LVR reaches its maximum length of 0.04%when the cement content is 6 mass%or 8 mass%.The increment of the cement content leads to a more intricate internal network structure,which hinders the reconstruction rate of the flocculated structure after high-shear deformation.
文摘In this work,the influences of surface layer slurry at different temperatures(10℃,14℃,18℃,22℃)on wax patterns deformation,shrinkage,slurry coating characteristics,and the surface quality of the casting were investigated by using a single factor variable method.The surface morphologies of the shell molds produced by different temperatures of the surface(first)layer slurries were observed via electron microscopy.Furthermore,the microscopic composition of these shell molds was obtained by EDS,and the osmotic effect of the slurry on the wax patterns at different temperatures was also assessed by the PZ-200 Contact Angle detector.The forming reasons for the surface cracks and holes of thick and large ZTC4 titanium alloy by investment casting were analyzed.The experimental results show that the surface of the shell molds prepared by the surface layer slurry with a low temperature exhibits noticeable damage,which is mainly due to the poor coating performance and the serious expansion and contraction of wax pattern at low temperatures.The second layer shell material(SiO_(2),Al_(2)O_(3))immerses into the crack area of the surface layer,contacts and reacts with the molten titanium to form surface cracks and holes in the castings.With the increase of the temperature of surface layer slurry,the damage to the shell surface tends to weaken,and the composition of the shell molds'surface becomes more uniform with less impurities.The results show that the surface layer slurry at 22℃is evenly coated on the surface of the wax patterns with appropriate thickness,and there is no surface shell mold rupture caused by sliding slurry after sand leaching.The surface layer slurry temperature is consistent with the wax pattern temperature and the workshop temperature,so there is no damage of the surface layer shell caused by expansion and contraction.Therefore,the shell mold prepared by the surface layer slurry at this temperature has good integrity,isolating the contact between the low inert shell material and the titanium liquid effectively,and the ZTC4 titanium alloy cylinder casting prepared by this shell mold is smooth,without cracks and holes.
基金support from the Scientific Research Foundation for the Introduction of Talent,Anhui University of Science and Technology(2023yjrc90)the Fundamental Research Funds of the AUST(2024JBQN0015)the Open Research Fund Program of Anhui Provincial Institute of Modern Coal Processing Technology,Anhui University of Science and Technology(MTY202302).
文摘The multipath application of green resources needs to be realised under the carbon neutrality goal.Worldwide,biomass is a resource in urgent need of treatment.In this paper,corn stover biomass(YM)or biochar with different particle sizes(YMF or YMX)was added during the preparation of coal-water slurry to investigate its effect on the performance of coal-water slurry and the micro-mechanism.The results showed that the fixed viscosity concentration of coal-water slurry(CYWS)with YM was only 47.42%,and the flowability was 49.9 mm,which made the slurry performance poor.The fixed viscosity concentration of coal-water slurry(CFWS)blended with YMF and coal-water slurry(CXWS)blended with YMX increased by 10.41%and 14.24%,respectively,compared with CYWS.Meanwhile,CXWS had the lowest thixotropy and yield stress,with a yield stress of only 16.13 Pa,which was 77.31 Pa lower than that of CYWS.This indicates that YMX treated by charring and milling is more favorable to be blended with coal to prepare coal-water slurry.This is due to the enhanced hydrophilicity and electronegativity of YMX.The enhanced hydrophilicity reduces the tendency to form three-dimensional networks in coal-water slurry,while the enhanced electronegativity improves the electrostatic repulsion between particles,which is beneficial to the dispersion of particles.In the subsequent EDLVO analyses,the same idea was proved.
基金financial support from the National Natural Science Foundation of China(No.52074137)the Yunnan Fundamental Research Projects,China(Nos.202301BE070001-054 and 202401CF070124)the Yunnan Major Scientific and Technological Projects,China(No.202403AA080001).
文摘Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosphogypsum.However,pipe plugging,which is caused by the poor workability of HPG-based filling materials,has become a major safety hazard in the filling process.Determining an economical and practicable method is urgently needed to improve the workability of HPG slurry work.First,this work found that grind-ing treatment was much more effective than increasing concentration(59wt%-65wt%)and adding tailings(20wt%-100wt%)in enhan-cing the workability of HPG slurry based on a comprehensive analysis of water retention,fluidity,and flow stability.Then,the combined effects of particle size,particle morphology,water film,and interparticle interactions on the workability of HPG slurry were quantitat-ively described through a microanalysis.Moreover,the first direct evidence for the transformation from robust embedded structures to soft stacking structures was presented.In practice,the filling materials should be prepared by grinding HPG for 20 min and mixing with 0-200wt%phosphorus tailings to achieve satisfactory workability and mechanical performance.The results of this study provide practic-al and feasible methods for addressing the stable transportation problem of HPG slurry.
基金supported by the Special Funds for Science and Technology Innovation on Carbon Peak Carbon Neutral of Jiangsu Province,China(No.BK20220017)the Natural Science Foundation of China(No.42007090)the National Key Research and Development Program of China(No.2021YFD22004)。
文摘Nitrous oxide(N_(2)O)emissions pose a serious environmental problem when nitrogen(N)fertilizer is excessively applied to plantation systems to enhance tree growth.Although biochar can improve soil fertility and mitigate soil N losses,our understanding of its interaction with N fertilizer and its long-term effects remains limited owing to experimental constraints.In this study,two microcosm incubation experiments were performed to evaluate the effect of fresh biochar,compared to 8-year field-aged biochar application in a poplar plantation,on soil N_(2)O emissions triggered by biogas slurry application.The experiments incorporated three biochar levels and four biogas slurry application rates,each with three replicates.The results demonstrated that fresh and aged biochar significantly reduced soil cumulative N_(2)O emissions by 31%–61%and 75%–99%,respectively,over 7 d following biogas slurry application.However,these mitigating effects diminished over incubation time.The application of fresh biochar significantly reduced soil available organic carbon and potential denitrification rates,suggesting that it primarily suppressed soil N_(2)O emissions by limiting the supply of electron donors.In contrast,aged biochar had minimal impact on soil available organic carbon and generally enhanced the abundances of bacterial amoA,nirS,nirK,and nosZ genes.This suggests that the aged biochar potentially suppressed soil N_(2)O emissions by promoting complete denitrification.Partial least squares structure equation model(PLS-SEM)analysis corroborated the two different mechanisms regulating the inhibitory influence of fresh and aged biochar on soil N_(2)O emissions.The lower R^(2)of PLS-SEM analysis for aged biochar(R^(2)=0.256)compared to that for fresh biochar(R^(2)=0.798)indicates that other factors,such as biochar properties,potentially affect soil N_(2)O emissions and warrant further investigation.This study highlights the need to evaluate the long-term effect of biochar on soil N_(2)O emissions,owing to the dynamic changes in biochar and soil properties over time.
基金Projects(52104355,52074363,52374364)supported by the National Natural Science Foundation of ChinaProject(2023YFC2907904)supported by the National Key R&D Program of China。
文摘Traditional pyrometallurgical and hydrometallurgical methods to extract bismuth from sulfide ores face problems such as high cost,low-concentration SO_(2)generation,and long process time.In this study,the cyclone technology and slurry electrolysis method were combined.The bismuth sulfide ore was dissolved directly at the anode,while the high purity bismuth was deposited efficiently at the cathode under the advantages of the two methods.The short process and high-efficiency extraction of bismuth sulfide ore were realized,and the pollution of low-concentration SO_(2)was avoided.Then,the effects of several crucial experimental conditions(current density,reaction time,temperature,pH,liquid-solid ratio,and circulation flow rate)on the leaching efficiency and recovery efficiency of bismuth were investigated.The leaching and electrowinning mechanisms during the recovery process were also analyzed according to the research results of this paper to better understand the cyclone slurry electrolysis process.The experimental results showed that 95.19%bismuth was leached into the acid solution in the anode area under optimal conditions,and the recovery efficiency and purity of bismuth on the cathode reached 91.13%and 99.26%,respectively,which were better than those by the traditional hydrometallurgy recovery process.
基金financially supported by the National Natural Science Foundation of China (No. 52062029)the Key Science and Technology Project of Gansu Province (No. 18YF1GA064)the Natural Science Foundation of Gansu Provence (No. 25JRRA094)。
文摘Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.
基金The authors gratefully acknowledge the filnancial support of the National Natural Science Foundation of China(Grant No.52369018)the Major Training Program of University Research and Innovation Platform of Gansu Provincial Department of Education(No.2024CXPT-09)+1 种基金the Administration of Central Funds Guiding the Local Science and Technology Development,China(Grant No.23ZYQA0320)the Double First-Class Key Program of Gansu Provincial Department of Education,Grant No.GCJ2022-38.
文摘Erosion in slurry pumps presents a persistent challenge in industrial applications.This study examines the erosion of the static components of a 150ZJ-C42 centrifugal slurry pump,currently in operation at a beneficiation plant,under varying particle conditions.Utilizing high-precision three-dimensional reverse engineering,the pump’s flow passage geometry was reconstructed to facilitate detailed erosion analysis.Focusing on the front and rear baffles of the pump chamber,as well as the volute,erosion patterns were analyzed for different particle volume concentrations and sizes.The results reveal that the highest erosion damage consistently occurs near the volute tongue,with wear being most severe in regions adjacent to the partition plate near the rear cover.Erosion damage intensity in this area correlates positively with particle diameter.Notably,the average erosion rate in the volute surpasses that of the front and rear chamber liners,reaching a value as high as 6.03×10^(-7)kg·m^(-2)·s^(-1)at a particle concentration of 9%and diameter of 0.1 mm,adversely impacting pump stability.For the pump chamber baffles,increased erosion is observed at a particle diameter of 0.05 mm under constant volume concentration conditions,while higher particle concentrations exacerbate localized erosion.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2023YJS053)the National Natural Science Foundation of China(Grant No.52278386).
文摘To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Undersea Tunnel.To evaluate the discharging performance of short screw conveyor in different cases,the full-scale transient slurry-rock two-phase model for a short screw conveyor actively discharging rocks was established using computational fluid dynamics-discrete element method(CFD-DEM)coupling approach.In the fluid domain of coupling model,the sliding mesh technology was utilized to describe the rotations of the atmospheric composite cutterhead and the short screw conveyor.In the particle domain of coupling model,the dynamic particle factories were established to produce rock particles with the rotation of the cutterhead.And the accuracy and reliability of the CFD-DEM simulation results were validated via the field test and model test.Furthermore,a comprehensive parameter analysis was conducted to examine the effects of TBM operating parameters,the geometric design of screw conveyor and the size of rocks on the discharging performance of short screw conveyor.Accordingly,a reasonable rotational speed of screw conveyor was suggested and applied to Jiaozhou Bay Second Undersea Tunnel project.The findings in this paper could provide valuable references for addressing the excavation chamber clogging during ultra-large-diameter slurry TBM tunneling in hard rock for similar future.
基金supported by the National Key R&D Program of China(2021YFA1501200)the National Natural Science Foundation of China(NSFC U23B20169 and 22021004)the Project of R&D Department of CNPC(2020B-2011)。
文摘The influences of reaction temperature,duration,pressure,and catalyst concentration on the molecular transformation of residual slurry phase hydrocracking process were investigated.The molecular composition of the heteroatom compounds in the residue feedstock and its upgrading products were characterized using high-resolution Orbitrap mass spectrometry coupled with multiple ionization methods.The simultaneous promotion of cracking and hydrogenation reactions was observed with increasing of the reaction temperature and time.Specifically,there was a significant increase in the cracking degree of alkyl side chain,while the removal of low-condensation sulfur compounds such as sulfides and benzothiophenes was enhanced.In particular,the cracking reactions were more significantly facilitated by high temperatures,while an appropriately extended reaction time can result in the complete elimination of the aforementioned sulfur compounds with a lower degree of condensation.Under conditions of low hydrogen pressure and catalyst concentration,the products still exhibit a high relative abundance of easily convertible compounds such as sulfoxides,indicating a significant deficiency in the effectiveness of hydrogenation.The hydrogen pressure exhibits an optimal value,beyond which further increments have no effect on the composition and performance of the liquid product but can increase the yield of the liquid product.At significantly high catalyst concentration,the effect of desulfurization and deoxidation slightly diminishes,while the aromatic saturation of highly condensed compounds was notably enhanced.This hydrogenation saturation effect cannot be attained through manipulation of other operational parameters,thereby potentially benefiting subsequent product processing and utilization.This present study demonstrates a profound comprehension of the molecular-level residue slurry phase hydrocracking process,offering not only specific guide for process design and optimization but also valuable fundamental data for constructing reaction models at the molecular level.
基金Project(5206800)supported by the National Natural Science Foundation of ChinaProject(2024JJA160096)supported by the Natural Science Foundation of Guangxi Province,China。
文摘Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water content and mud water separation rate was established to achieve efficient resource utilization,and the feasibility of foam lightweight soil(FLS)prepared from BT was investigated.The effects of industrial waste residues(fly ash and slag powder)on the properties of FLS were studied.Meanwhile,the micro-mechanisms were revealed by XRD,SEM-EDS,and TG-DSC.The results revealed that fly ash reduced the workability and compressive strength of FLS.Slag powder can significantly enhance the compressive strength of FLS,which increased by 18.60%-23.26%,17.07%-58.54% and 12.12%-52.12%,respectively.Besides,slag powder can improve the long-term water stability performance and enhance carbonation resistance.XRD and thermal analyses showed that adding fly ash decreased the hydration degree of FLS,leading to a decrease in the hydration products.Slag powder improved the pore structure and compacted the skeleton structure of FLS.This study would provide an effective way to realize the resource utilization of BT,fly ash,and slag powder,with certain socio-economic and environmental benefits.
基金supported by the Fundamental Research Funds for the Central Universities(No.02302350113).
文摘Shallow-buried thick sand strata present considerable local instability risks during diaphragm wall trenching construction.However,this critical issue has not been extensively studied,despite its serious safety consequences.This paper proposes an automatic identification model for shallow-buried thick sand strata,integrating three-dimensional limit equilibrium theory with a genetic algorithm to precisely identify the most potentially dangerous local instability mass and determine its minimum safety factor.The model establishes three undetermined parameters:failure angle,upper boundary,and thickness of the local instability mass.These parameters define the search space for the local instability mass.The effectiveness of this approach was confirmed through a diaphragm wall engineering case near the Rhine River in France,where the predicted instability location closely aligned with field observations.A systematic analysis of the model indicated that the difference in slurry-groundwater levels and the friction angle are the most significant factors affecting local instability in shallow-buried thick sand strata.The model indicated that the location of the most potentially dangerous instability mass changes depending on geological conditions,and larger instability masses do not always relate to lower safety factors.Additionally,exploratory experiments revealed that support pressure losses caused by slurry infiltration significantly influence local instability calculations in sand strata.This points out the importance of considering these support pressure losses in the stability evaluations of high permeable sand strata.The results improve the evaluation of safety and the optimization of design for diaphragm wall construction in shallow-buried thick sand strata.
基金partially sponsored by the Office of Energy Efficiency and Renewable Energy(EERE)in the Vehicle Technologies Office(VTO)through the Advanced Battery Materials Research(BMR)Program,managed by DrsThe Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan(http://energy.gov/downloads/doe-public-access-plan).
文摘We demonstrate for the first time the critical influence of binder molecular weight on the performance of slurry-cast lithium nickel manganese cobalt oxide(NMC)cathodes in sulfide-based all-solid-state batteries(SSBs).SSBs are increasingly recognized as a safer and potentially more efficient alternative to traditional Li-ion batteries,owing to the superior ionic conductivities and inherent safety features of sulfide solid electrolytes.However,the integration of high-voltage NMC cathodes with sheet-type sulfide solid electrolytes presents significant fabrication challenges.Our findings reveal that higher molecular weight binders not only enhance the discharge capacity and cycle life of these cathodes but also ensure robust adhesion and structural integrity.By optimizing binder molecular weights,we effectively shield the active materials from degradation and mechanical stress,significantly boosting the functionality and longevity of SSBs.These results underscore the paramount importance of binder properties in advancing the practical application of high-performance all-solid-state batteries.
基金The National Natural Science Foundation of China,Grant/Award Number:42130706。
文摘Due to the invisibility and complexity of the underground spaces,monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging,which complicates engineering treatment.This research investigated the propagation law of cement-sodium silicate slurry under flowing water conditions within the caving mass of a metal mine.First,based on borehole packer test results and borehole TV images,the fractured strata before grouting were classified into four types:cavity,hidden,fissure,and complete.Second,an orthogonal experimental design was employed to evaluate the impact of four key factors—stratigraphic fragmentation,water flow rate,grouting flow rate,and water-cement ratio—on the efficacy of grouting within a caving mass at the site.The results indicate that the factors influencing grouting efficacy are ranked in the following order of importance:stratigraphic fragmentation>water flow rate>water–cement ratio>grouting flow rate.Ultimately,five propagation filling modes—pure slurry,big crack,small crack,small karst pore,and pore penetration—were identified by examining the propagation filling characteristics of slurry in rock samples,incorporating microscopic material structure analysis through scanning electron microscopy and energy spectrum analysis.The findings of this study provide valuable insights into selecting engineering treatment parameters and methodologies,serving as a reference for preventing and controlling water–sand mixture inrush in metal mines,thereby enhancing treatment efficacy and ensuring grouting success.
基金supported by the National Key Research and Development Program(2021YFB3501103)Guiding Local Funding Projects for Scientific and Technological Development by Central Government in Hebei(216Z1402G)Youth Fund of GRINM Group Co.,Ltd.
文摘The lanthanum-cerium-based slurry(LC-slurry)is extensively utilized in the chemical mechanical polishing(CMP)of TFT-LCD glass substrates,optical lenses,and other glass products.Sodium hexametaphosphate(SHMP),as a dispersant,is commonly employed to enhance the dispersion properties of LCslurry for improved polishing performance.However,the tendency of sedimentation to form a compacted sediment layer,which is challenging to redisperse,increases storage difficulty and polishing equipment failure risk,thereby limiting its utilization in CMP.In the present study,sodium carboxymethylcellulose(CMC-Na),a long-chain organic polymer,was employed to enhance the redispersibility of LC-slurry containing SHMP.A comprehensive investigation was conducted on the influence of CMC-Na dosage and slurry pH on dispersibility,redispersibility and polishing performance.Additionally,an analysis was carried out to elucidate the underlying mechanism behind the effect of CMC-Na.The study demonstrates that the LC-slurry,containing 250 ppm SHMP and 500 ppm CMC-Na,exhibits excellent dispersibility and redispersibility.Further polishing tests demonstrate that compared to the LC-slurry containing only SHMP,utilizing the slurry containing both SHMP and CMC-Na at various pH for polishing thin film transistor liquid crystal display(TFT-LCD)glass substrates results in a reduction of both material removal rate(MRR)and surface roughness(Sa).Specifically,when adjusting the slurry to a pH range of 5-6,the MRR can reach up to 330 nm/min,which closely approximates the MRR achieved by LC-slurry containing only 250 ppm SHMP at corresponding pH values.Meanwhile,after polishing,the surface roughness of the glass substrate measures approximately 0.47 nm.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA28100200)the National Key Research and Development Program of China(2022YFD150080202)+1 种基金the Key Laboratory of Low-carbon Green Agriculture in Northeastern China,Ministry of Agriculture and Rural Affairs of the People’s Republic of China(LCGANE12)the Northeast Agricultural University Scholar Project and Academic Backbones Program(20YJXG13)。
文摘Dairy cattle slurry is a source of nitrogen(N)that can substitute for synthetic fertilizers.This study aimed to identify combinations of synthetic fertilizers and slurry optimal for maize growth and N dynamics in Northeast China.In a two-year field experiment testing synthetic-to-slurry N fertilization ratios,slurry application increased grain yield and yield components,net economic benefit,and N use efficiency relative to synthetic fertilization but led to higher nitrous oxide and ammonia emissions.A 1:1-1:3 synthetic N:slurry N ratio and slurry application at 60-90 t ha^(-1)balanced productivity with N losses.
基金supported by the National Natural Science Foundation of China(Grant Nos.52375210 and 52375209)Yangzhou City and Yangzhou University Cooperation Foundation(Grant No.YZ2022182)+2 种基金Yangzhou Science and Technology Plan Project(Grant No.YZ2023246)Postgraduate Research and Practice Innovation Program of Jiangsu Province(Grant No.SJCX23_1902)Qing Lan Project of Yangzhou University.
文摘The mathematical model between laser cladding parameters and coating properties was established by the response surface method(RSM).Ni–WC-reinforced CoCrNiFeAl high-entropy alloy(HEA)composite coatings were prepared on the surface of 0Cr13Ni5Mo steel by laser cladding to study the addition of Ni–WC on slurry erosion resistance of coatings.The optimal parameters obtained by RSM are laser power of 1450 W,scanning speed of 4.3 mm/s,powder feeding speed of 1.3 r/min and overlap rate of 60%,respectively.The grains of CoCrNiFeAl composite coatings are refined by adding Ni–WC-reinforced powder.15 wt.%Ni–WC composite coating presents the maximum microhardness with the value of 655 HV_(0.3).The cumulative mass loss of the composite coatings at different erosion angles is lower than that of the pure CoCrNiFeAl coating.In addition,at low erosion angles,the cumulative mass loss of the composite coatings gradually decreases with the increase in the mass fraction of Ni–WC.Ploughing and microcutting are the primary erosion mechanisms of CoCrNiFeAl composite coatings at low erosion angles.When erosion damage occurs at high erosion angle,the erosion mechanisms of composite coating material loss are dominated by lip formation and craters.The proposed high-entropy alloy composite coatings can be applied to improve the erosion resistance of components in contact with high-speed fluids,such as ship propellers and centrifugal pump blades.
文摘Reef limestone is buried in the continental shelf and marine environment.Understanding the mechanisms governing filter cake formation in coral reef limestone strata is essential for various engineering activities in coastal areas,including slurry pressure balanced(SPB)shield tunneling,which are currently not well understood.This study systematically investigates the slurry infiltration characteristics of different coral reef limestone types with inherent anisotropy,identified by growth line orientations,through a series of micro-infiltration column tests.Multiple slurry concentrations and pressures were used to analyze their effects on slurry infiltration dynamics and filter cake formation.Pre-and post-infiltration CT scanning was conducted to examine skeletal morphology and reconstruct the pore network structure of coral reef limestone samples.The results show that while increased slurry concentrations and pressures generally improve filter cake formation,excessive pressure can compromise filter cake integrity.By employing Dijkstra’s algorithm in a pore network model,the study identified primary seepage pathways,highlighting the significant role of near-vertical throat clusters in the infiltration process.A comprehensive analysis of pore structure and connectivity indices before and after infiltration revealed that the orientation of growth lines in coral reef limestone is the primary factor influencing macroscopic slurry infiltration behavior.These findings offer valuable insights for the design and execution of tunneling projects through coral reef limestone formations,especially in coastal regions.
基金Funded by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(No.SKLGP2022Z001)。
文摘We examined the mechanical strength and microscopic property effects of bottom ash(BA)recycled concrete made by partially substituting natural aggregates made from three industrial wastes,fly ash(FA),silica fume(SF),furnace slag(FS),and cement after BA was treated with slurry to improve the properties of BA and increase its utilisation.The compressive,flexural,splitting tensile strengths,and drying shrinkage test of the recycled concrete from BA were tested at the macroscopic level,and the specimens were analyzed by scanning electron microscopy(SEM)at the microscopic level.The experimental results show that the slurry treatment of BA results in a corresponding improvement in the macroscopic and microscopic properties of the obtained slurry-bound BA aggregates.The synergistic effect of FA and SF can better fill the pores on the surface of BA,which in turn can better improve the properties of recycled concrete.This study provides a theoretical support for improving the properties of BA and promoting its utilisation as a resource.
文摘In this paper is presented a concept solution and acceptance test application procedure of deep pit protection structure,intended for three underground levels of residential building:A,B,C,D,block 10C,Budva,Montenegro.The anchored wall used consist of nongravity cantilevered walls with three levels of ground anchors.Nongravity cantilevered walls employ continuous walls constructed in slurry trenches(i.e.,slurry(diaphragm)walls),e.g vertical elements that are drilled to depths below the finished excavation grade.For those nongravity cantilevered walls,support is provided through the shear and bending stiffness of the vertical wall elements and passive resistance from the soil below the finished excavation grade.Anchored wall support relies on these components as well as lateral resistance provided by the ground anchors to resist horizontal pressures(e.g.,earth,water,external loads)acting on the wall.Anchored wall analysed and applied is temporary supporting structure necessary for the excavation and erection of the underground structure part up to ground surface level.Temporary ground anchors lifetime is up to two years.Dynamic loads are not considered.
