Evolution of nonmetallic inclusions in 80-t 9CrMoCoB large-scale ingots during electroslag remelting process

In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrMoCoB heat-resistant steel and CaF_(2)–CaO–Al_(2)O_(3)–SiO_(2)–B_(2)O_(3)electroslag remelting(ESR)-type slag in an 80-t industrial ESR furnace.The main types of NMI in the consumable electrode comprised pure alumina,a multiphase oxide consisting of an Al_(2)O_(3)core and liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO shell,and M_(23)C_(6)carbides with an MnS core.The Al_(2)O_(3)and MnS inclusions had higher precipitation temperatures than the M_(23)C_(6)-type carbide under equilibrium and nonequilibrium solidification processes.Therefore,inclusions can act as nucleation sites for carbide layer precipitation.The ESR process completely removed the liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO oxide and MnS inclusion with a carbide shell,and only the Al_(2)O_(3)inclusions and Al_(2)O_(3)core with a carbide shell occupied the remelted ingot.The M_(23)C_(6)-type carbides in steel were determined as Cr_(23)C_(6)based on the analysis of transmission electron microscopy results.The substitution of Cr with W,Fe,or/and Mo in the Cr_(23)C_(6)lattice caused slight changes in the lattice parameter of the Cr_(23)C_(6)carbide.Therefore,Cr_(21.34)Fe_(1.66)C_(6),(Cr_(19)W_(4)C_(6),Cr_(18.4)Mo_(4.6)C_(6),and Cr_(16)Fe_(5)Mo_(2)C_(6)can match the fraction pattern of Cr_(23)C_(6)carbide.The Al_(2)O_(3)inclusions in the remelted ingot formed due to the reduction of CaO,SiO_(2),and MnO components in the liquid inclusion.The increased Al content in liquid steel or the higher supersaturation degree of Al_(2)O_(3)precipitation in the remelted ingot than that in the electrode can be attributed to the evaporation of CaF_(2)and the increase in CaO content in the ESR-type slag.

Critical precipitation behavior of MnTe inclusions in resulfurized steels during solidification

Te treatment is an effective method for modifying sulfide inclusions,and MnTe precipitation has an important effect on thermal brittleness and steel corrosion resistance.In most actual industrial applications of Te treatment,MnTe precipitation is unexpected.The critical precipitation behavior of MnTe inclusions was investigated through scanning electron microscopy,transmission electron microscopy,machine learning,and first-principles calculation.MnTe preferentially precipitated at the container mouth for sphere-like sulfides and at the interface between MnS grain boundaries and steel matrix for rod-like sulfides.The MnS/MnTe interface was semicoherent.A composition transition zone with a rock-salt structure exhibiting periodic changes existed to maintain the semicoherent interface.The critical precipitation behavior of MnTe inclusions in resulfurized steels involved three stages at varying temperatures.First,Mn(S,Te)precipitated during solidification.Second,MnTe with a rock-salt structure precipitated from Mn(S,Te).Third,MnTe with a hexagonal NiAs structure transformed from the rock-salt structure.The solubility of Te in MnS decreased with decreasing temperature.The critical precipitation behavior of MnTe inclusions in resulfurized steels was related to the MnS precipitation temperature.With the increase in MnS precipitation temperature,the critical Te/S weight ratio decreased.In consideration of the cost-effectiveness of Te addition for industrial production,the Te content in resulfurized steels should be controlled in accordance with MnS precipitation temperature and S content.

Dissolution behavior of Al_(2)O_(3)inclusions into CaO-MgO-SiO_(2)-Al_(2)O_(3)-TiO_(2)system ladle slags

To investigate the dissolution behaviors of Al_(2)O_(3)inclusions in CaO-5wt%MgO-SiO_(2)-30wt%Al_(2)O_(3)-TiO_(2)system ladle slags,confocal scanning laser microscopy was conducted on the slags with different TiO_(2)contents(0-10wt%),and scanning electron microscopy was performed to study the interfacial reaction between Al_(2)O_(3)and this slag system.The results disclose that the dissolution of Al_(2)O_(3)inclusions does not result in the formation of new phases at the boundary between the slag and the inclusions.In TiO_(2)-bearing and TiO_(2)-free ladle slags,there is no difference in the dissolution mechanism of Al_(2)O_(3)inclusions at steelmaking temperatures.Boundary layer diffusion is found as the controlling step of the dissolution of Al_(2)O_(3),and the diffusion coefficient is in the range of 4.18×10^(-10)to 2.18×10^(-9)m^(2)/s at 1450-1500℃.Compared with the solubility of Al_(2)O_(3)in the slags,slag viscosity and temperature play a more profound role in the dissolution of Al_(2)O_(3)inclusions.A lower viscosity and a lower melting point of the slags are beneficial for the dissolution.Suitable addition of TiO_(2)(e.g.,5wt%)in ladle slags can enhance the dissolution of Al_(2)O_(3)inclusions because of the low viscosity and melting point of the slags,while excessive addition of TiO_(2)(e.g.,10wt%)shows the opposite trend.

Genesis of the Jianbeigou Gold Deposit on the Southern Margin of the North China Craton: Insights from Fluid Inclusions, H-O-S Isotopes, and Pyrite in situ Trace Element Analyses

The Jianbeigou gold deposit is a typical lode gold deposit in the Qinling metallogenic belt, located on the southern margin of the North China Craton. Three stages of the hydrothermal process can be distinguished, including the quartz ± pyrite, quartz-polymetallic sulfide, and quartz-carbonate ± pyrite stages. From the early to late stages, the homogenization temperatures of primary fluid inclusions are 281–362°C, 227–331°C, and 149–261°C, respectively. The corresponding salinities estimated for these fluids are 3.9–9.9 wt%, 0.4–9.4 wt%, and 0.7–7.2 wt% Na Cl equiv. Combined with laser Raman spectroscopy data, the ore-forming fluid belongs to a H_(2)O-CO_(2)-Na Cl ± CH_4 system with medium–low temperature and salinity. The δ~(18)Ofluid and δD values for the quartz veins are-1.0‰ to 6.0‰ and-105‰ to-84‰, respectively, which indicates that the ore-forming fluid is of mixed source, mainly derived from magma, with a contribution from meteoric water. Pyrite has been identified into three generations based on mineral paragenetic sequencing, including Py1, Py2, and Py3. The pyrites have δ~(34)S sulfur isotopic compositions from three stages between 3.7‰ and 8.4‰, indicating that sulfur mainly originated from magma. Te, Bi, Sb, and Cu contents in pyrite were all high and showed a strong correlation with Au concentrations. Native gold and the Au-Ag-Bi telluride minerals were formed concurrently, and the As concentration was low and decoupled from the Au content. Therefore, Te, Bi, Sb and other low-melting point chalcophile elements play an important role for gold mineralization in arsenic-deficient ore-forming fluid. Combined with the geological setting, evolution of pyrite, and ore-fluids geochemistry, we propose that the Jianbeigou deposit can be classified as a magmatic–hydrothermal lode gold deposit. Gold mineralization on the southern margin of the North China Craton is related to Early Cretaceous magmatism and formed in an extensional setting.

Shock-induced energy localization and reaction growth considering chemical-inclusions effects for crystalline explosives

Chemical inclusions significantly alter shock responses of crystalline explosives in macroscale gap experiments but their microscale dynamics origin remains unclear.Herein shock-induced energy localization,overall physical responses,and reactions in a-1,3,5-trinitro-1,3,5-triazinane(a-RDX)crystal entrained various chemical inclusions were investigated by the multi-scale shock technique implemented in the reactive molecular dynamics method.Results indicated that energy localization and shock reaction were affected by the intrinsic factors within chemical inclusions,i.e.,phase states,chemical compositions,and concentrations.The atomic origin of chemical-inclusions effects on energy localization is dependent on the dynamics mechanism of interfacial molecules with free space volume,which includes homogeneous intermolecular compression,interfacial impact and shear,and void collapse and jet.As introducing various chemical inclusions,the initiation of those dynamics mechanisms triggers diverse decay rates of bulk RDX molecules and hereby impacts on growth speeds of final reactions.Adding chemical inclusions can reduce the effectiveness of the void during the shock impacting.Under the shockwave velocity of 9 km/s,the parent RDX decay rate in RDX entrained amorphous carbon decreases the most and is about one fourth of that in RDX with a vacuum void,and solid HMX and TATB inclusions are more reactive than amorphous carbon but less reactive than dry air or acetone inclusions.The lessdense shocking system denotes the greater increases in local temperature and stress,the faster energy liberation,and the earlier final reaction into equilibrium,revealing more pronounced responses to the present intense shockwave.The quantitative models associated with the relative system density(RD_(sys))were proposed for indicating energy-localization mechanisms and evaluating initiation safety in the shocked crystalline explosive.RD_(sys)is defined by the density ratio of defective RDX to perfect crystal after dynamics relaxation and reveals the global density characteristic in shocked systems filled with chemical inclusions.When RD_(sys)is below 0.9,local hydrodynamic jet initiated by void collapse dominates upon energy localization instead of interfacial impact.This study sheds light on novel insights for understanding the shock chemistry and physical-based atomic origin in crystalline explosives considering chemical-inclusions effects.

Magmatic-hydrothermal Evolution and Mineralization Mechanisms of the Wangjiazhuang Cu(-Mo)Deposit in the Zouping Volcanic Basin,Shandong Province,China:Constraints from Fluid Inclusions

The Wangjiazhuang Cu(-Mo)deposit,located within the Zouping volcanic basin in western Shandong Province,China,is unique in this area for having an economic value.In order to expound the metallogenetic characteristics of this porphyry-like hydrothermal deposit,a detailed fluid inclusion study has been conducted,employing the techniques of representative sampling,fluid inclusion petrography,microthermometry,Raman spectroscopy,LA-ICP-MS analysis of single fluid inclusions,as well as cathode fluorescence spectrometer analysis of host mineral quartz.The deposit contains mainly two types of orebodies,i.e.veinlet-dissemination-stockwork orebodies in the K-Si alteration zone and pegmatiticquartz sulfide veins above them.In addition,minor breccia ore occurs locally.Four types of fluid inclusions in the deposit and altered quartz monzonite are identified:L-type one-or two-phase aqueous inclusions,V-type vapor-rich inclusions with V/L ratios greater than 50%-90%,D-type multiphase fluid inclusions containing daughter minerals or solids and S-type silicate-bearing fluid inclusions containing mainly muscovite and biotite.Ore petrography and fluid inclusion study has revealed a three-stage mineralization process,driven by magmatic-hydrothermal fluid activity,as follows.Initially,a hydrothermal fluid,separated from the parent magma,infiltrated into the quartz monzonite,resulting in its extensive K-Si alteration,as indicated by silicate-bearing fluid inclusions trapped in altered quartz monzonite.This is followed by the early mineralization,the formation of quartz veinlets and dissemination-stockwork ores.During the main mineralization stage,due to the participation and mixing of meteoric groundwater with magmatic-sourced hydrothermal fluid,the cooling and phase separation caused deposition of metals from the hydrothermal fluids.As a result,the pegmatitic-quartz sulfide-vein ores formed.In the late mineralization stage,decreasing fluid salinity led to the formation of L-type aqueous inclusions and chalcopyrite-sulfosalt ore.Coexistence of V-type and D-type inclusions and their similar homogenization temperatures with different homogenization modes suggest that phase separation or boiling of the ore-forming fluids took place during the early and the main mineralization stages.The formation P-T conditions of S-type inclusions and the early and the main mineralization stages were estimated as ca.156-182 MPa and 450-650℃,350-450℃,18-35 MPa and 280-380℃,8-15 MPa,respectively,based on the microthermometric data of the fluid inclusions formed at the individual stages.

Microthermometry and Synchrotron Radiation X-ray Fluorescence Analysis of Fluid Inclusions in the Dongping Gold Deposit,Northern Margin of the North China Craton

To shed light on the genesis of the Dongping deposit and reveal the behaviour of CO_(2),Au and other ore elements(e.g.,Cu,Fe,Zn,As,Sb,Co etc.)in ore-forming fluids,petrographic,microthermometric and synchrotron radiation X-ray fluorescence(SRXRF)analyses of fluid inclusions were conducted.The ore-forming fluid is characterized as an H_(2)O-CO_(2)-NaCl system with medium-high temperatures and low salinity.Four mineralization stages are identified,namely,feldsparquartz(stage 1);pyrite-white quartz(stage 2);sulfide-smoky grey quartz(stage 3);and carbonate-quartz(stage 4).Three types of inclusions were distinguished,based on fluid composition,phase assemblages and mode of homogenization.Type A:H_(2)O-rich fluid inclusions show 2 phases(liquid H_(2)O(LH_(2)O)+vapour H_(2)O(VH_(2)O))at room temperature and homogenize to the liquid phase.Type B:H_(2)O-CO_(2)fluid inclusions contain 2–3 phases(liquid H_(2)O(LH_(2)O)+vapour CO_(2)(VCO_(2));liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2)));liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2))+vapour CO_(2)(VCO_(2)))at room temperature and homogenized to the liquid H_(2)O phase.Type C:H_(2)O-CO_(2)fluid inclusions show 2 phases(liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2))at room temperature and homogenize to a critical state.CO_(2)is clearly more enriched in the fluid inclusions of stages 2 and 3 than in stage 1.Stage 1 is dominated by type A(H_(2)O-rich)inclusions with homogenization temperatures(Th)of 220–359℃and salinities of 1.1–3.1 wt%NaCl equivalent.Type B(CO_(2)-rich)inclusions gradually increase in stages 2 and 3.The Th range of type B inclusions in stage 2 is 241–397℃with salinities of 2.2–6.9 wt%NaCl equivalent;the Th range of type A inclusions is 217–373℃with salinities of 1.2–8.1 wt%NaCl equivalent.The Th range of type B inclusions in stage 3 is 215–361℃with salinities of 2.9–6.1 wt%NaCl equivalent;the range of type A inclusions is 158–351℃with a salinity of 0.7–5.5 wt%NaCl equivalent.Stage 4 is characterized by type A with Th of 151–250℃and salinities of 0.9–8.3 wt%NaCl equivalent.The mapping results show that elements As,Te and Sb are more concentrated in vapour CO_(2)than in liquid H_(2)O at room temperature,which suggests that vapour components are more able to transport elements when phase separation occurs.The SRXRF quantitative results show that Au,Cl,S and some other metals are obviously more enriched in the fluid inclusions of stages 2 and 3 than those in stage 1.Additionally,the contents of S in stages 1–3 are much lower than those of Cl,which suggests that gold might migrate mainly in the form of a gold-chloride complex.Au is more enriched in type B fluid inclusions than in type A fluid inclusions,which suggests that the enrichment and migration of gold are closely related to CO_(2)and CO_(2)plays a critical role in the migration and enrichment of gold.The trace elements in the fluid have a similar change trend to those in the Yanshanian syenogranite distributed in the southeastern part of the mining area,which may provide some evidence for an intrusion-related genesis for the Dongping gold deposit.

Carbon Enrichment in the Lithospheric Mantle:Evidence from the Melt Inclusions in Mantle Xenoliths from the Hainan Basalts

It is generally believed that the lithospheric mantle and the mantle transition zone are important carbon reservoirs.However,the location of carbon storage in Earth's interior and the reasons for carbon enrichment remain unclear.In this study,we report CO_(2)-rich olivine-hosted melt inclusions in the mantle xenoliths of late Cenozoic basalts from the Penglai area,Hainan Province,which may shed some light on the carbon enrichment process in the lithospheric mantle.We also present a detailed petrological and geochemical investigation of the late Cenozoic basalts and mantle xenoliths from northern Hainan Island.The collected samples of late Cenozoic Hainan Island basalts belong to both alkaline and subalkaline series,showing fractionated REE patterns with high(La/Yb)_(N)values of 3.52–11.77,which are typical for OIB.Based on Al-in-olivine thermometry,the temperatures estimated for the mantle xenoliths can be divided into two groups.One group has temperatures of less than 1050℃,and the other group has temperature ranging from 1050℃to 1282℃.Clinopyroxene(La/Yb)_(N)–Ti/Eu and clinopyroxene Ca/Al–Mg^(#)diagrams indicate that the mantle peridotite experienced metasomatism from both silicate and carbonate melts.Melt inclusions in the olivine of mantle xenoliths include(1)CO_(2)bubble–rich melt inclusions;(2)multiphase melt inclusions(glass+CO_(2)bubble+daughter minerals);(3)pure glass melt inclusions.Magnesite is a daughter mineral in the olivine-hosted melt inclusions,which could be interpreted as a secondary mineral formed by the interactions of CO_(2)-rich fluids with an olivine host,due to post-entrapment effects.The glasses in olivine-hosted melt inclusions have high SiO_(2)contents(60.21–77.72 wt%).Our results suggest that a considerable amount of CO_(2)-rich melt inclusions are captured in the lithospheric mantle during metasomatism.The lithospheric mantle can therefore act as is a‘carbon trap',with much CO_(2)being absorbed by the lithospheric mantle in this way.

Thermodynamics of Modifying Effect of Rare Earth Oxide on Inclusions in Hardfacing Metal of Medium-High Carbon Steel

The modifying effect of rare earth (RE) oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics. The thermodynamic analysis for inclusion formation shows that RE oxide can be reduced to RE element by carbon, then the RE element can react with oxygen and sulfur to form the RE oxide, RE sulfide and RE oxide-sulfide in hardfacing molten pool. The deoxidization and the desulphurization can be carried out and the liquid metal can be purified. In addition, RE oxide can also react with sulfur to form RE oxide-sulfide directly. Therefore, the harmful effect of sulfur can be decreased.

Experimental studies on the evolution process of microcrack patterns in concrete samples con-taining hard inclusions

Under biaxial pressure, the microcrack patterns of concrete samples with hard inclusion are as followings: Microcracks generate around the sample at the early pressured period, and gap is formed in the middle part with the increase of σ 1; microcrack gap is becoming smaller gradually with σ 1 increase again; microcracks become active within the original gap, but they in an original active area become small. Approaching the main fracture, microcracks form as a belt and jump back and forth in the belt. The spatial fractal D s of microcracks changes from small to big, but turns decrease when approaching the main fracture. All of the features were seldom mentioned in the past experiment, however, which have some similarities with the long seismicity patterns before strong earthquakes. In this paper, Lancang Gengma earthquake was taken as an example to analyse.〖KH*2D]

Discussion of RE Inclusions as Heterogeneous Nuclei of Primary Austenite in Hardfacing Metals of Medium-High Carbon Steels

As the substrate for nucleation of primary austenite in hardfacing metals, the effectiveness of RE inclusions and the most common inclusions such as Al2O3, SiO2 and MnO in hardfacing metals of medium-high carbon steels was analyzed and calculated in detail. The calculation based on the theory of planar lattice misfit shows that Ce2O3, La2O3 and Ce2O2S, instead of SiO2, Al2O3, MnO and CeS, are effective as the heterogeneous nuclei of primary austenite in medium-high carbon steels.

Dissolution of TiO_(2) and TiN inclusions in CaO–SiO_(2)–B_(2)O_(3)-based fluorine-free mold flux

Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mechanism of Ti O_(2)and Ti N inclusions in molten Ca O–Si O_(2)–B_(2)O_(3)-based fluorine-free mold flux were explored by in situ single hot thermocouple technology combined with X-ray photoelectron spectroscopy.The results showed that Ti O_(2) inclusions are effectively dissolved by the molten slag within 76 s, during which the original octahedral [Ti O_(6)]^(8-)structures are destroyed and convert to the networker tetrahedral [Ti O_(4)]^(4-)structures. However, the dissolution rate is much lower for Ti N inclusions than for Ti O_(2)inclusions. This can be attributed to the fact that the Ti N particles need to be oxidized and then dissolved in the molten slag to form tetrahedral [Ti O4]4-and octahedral [Ti O_(6)]^(8-)structures during the Ti N inclusion dissolution process, which is accompanied by the generation of a large amount of N_(2)gas. Moreover, Ca Ti O_(3)crystals tend to nucleate and grow on bubble surfaces with sufficient octahedral [Ti O_(6)]^(8-)structures and Ca^(2+)ions, eventually resulting in the molten slag being in a solid–liquid mixed state.

Lignin-derived hard carbon anode with a robust solid electrolyte interphase for boosted sodium storage performance

Hard carbon is regarded as a promising anode candidate for sodium-ion batteries due to its low cost,relatively low working voltage,and satisfactory specific capacity.However,it still remains a challenge to obtain a high-performance hard carbon anode from cost-effective carbon sources.In addition,the solid electrolyte interphase(SEI)is subjected to continuous rupture during battery cycling,leading to fast capacity decay.Herein,a lignin-based hard carbon with robust SEI is developed to address these issues,effectively killing two birds with one stone.An innovative gas-phase removal-assisted aqueous washing strategy is developed to remove excessive sodium in the precursor to upcycle industrial lignin into high-value hard carbon,which demonstrated an ultrahigh sodium storage capacity of 359 mAh g^(-1).It is found that the residual sodium components from lignin on hard carbon act as active sites that controllably regulate the composition and morphology of SEI and guide homogeneous SEI growth by a near-shore aggregation mechanism to form thin,dense,and organic-rich SEI.Benefiting from these merits,the as-developed SEI shows fast Na+transfer at the interphases and enhanced structural stability,thus preventing SEI rupture and reformation,and ultimately leading to a comprehensive improvement in sodium storage performance.

Textural and functional analysis of sorghum flour cookies as ice cream inclusions

Flour serves as one of the primary ingredients of cookies,which affects dough properties,physical changes during baking,and post-baking cookie properties.Two gluten-free cookie formulations were developed with the goal of use as inclusions in frozen desserts.Blonde and chocolate cookies were made with sorghum flour or all-purpose wheat flour and then evaluated for physical and chemical properties.To determine functionality in a frozen state,texture analysis was conducted on cookies at−30℃,−17°C,and 20℃,replicating various ice cream storage temperatures.To simulate the process effect of incorporating the product into a frozen dessert,cookies were crumbled mechanically,and the crumbles were separated based on size.When evaluating cookies,no significant differences(P<0.05)were observed in width(W),thickness(T),spread,and W/T ratio for flour source within formula.Blonde cookies had lower moisture contents than chocolate cookies;further,blonde cookies made from sorghum flour had less moisture than those made with wheat flour.As the cookie temperature decreased from 20℃to−17℃,cookie hardness increased,with flour type having no effect.Within formula,cookies had similar instrumental color parameters.However,blonde cookies made from sorghum flour produced more smaller-sized pieces than those made from wheat flour.The results of this study demonstrate that sorghum flour cookies have desirable properties for use as inclusions in ice cream and other frozen desserts.

Failure mechanism and infrared radiation characteristic of hard siltstone induced by stratification effect

The deformation in sedimentary rock induced by train loads has potential threat to the safe operation of tunnels. This study investigated the influence of stratification structure on the infrared radiation and temporal damage mechanism of hard siltstone. The uniaxial compression tests, coupled with acoustic emission(AE) and infrared radiation temperature(IRT) were conducted on siltstones with different stratification effects. The results revealed that the stratigraphic structure significantly affects the stress-strain response and strength degradation characteristics. The mechanical parameters exhibit anisotropy characteristics, and the stratification effect exhibits a negative correlation with the cracking stress and peak stress. The failure modes caused by the stratification effect show remarkable anisotropic features, including splitting failure(Ⅰ: 0°-22.50°, Ⅱ: 90°), composite failure(45°), and shearing failure(67.50°). The AE temporal sequences demonstrate a stepwise response characteristic to the loading stress level. The AE intensity indicates that the stress sensitivity of shearing failure and composite failure is generally greater than that of splitting failure. The IRT field has spatiotemporal migration and progressive dissimilation with stress loading and its dissimilation degree increases under higher stress levels. The stronger the stratification effect, the greater the dissimilation degree of the IRT field. The abnormal characteristic points of average infrared radiation temperature(AIRT) variance at local stress drop and peak stress can be used as early and late precursors to identify fracture instability. Theoretical analysis shows that the competitive relationship between compaction strengthening and fracturing damage intensifies the dissimilation of the infrared thermal field for an increasing stress level. The present study provides a theoretical reference for disaster warnings in hard sedimentary rock mass.

Free radicals trigger the closure of open pores in lignin-derived hard carbons toward improved sodium-storage capacity

The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage.However,the formation mechanism of closed pores under the influence of pore-forming agents is not well understood.Herein,an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores in lignin-derived hard carbon(HCs).By systematic experimental design combined with electron paramagnetic res-onance spectroscopy,it can be found that the content of free radicals in the carbon matrix influences the closure of open pores at high temperatures.Excessively high activation temperature(>700 C)leads to a low free radical concentration,making it difficult to achieve self-healing of open pores at high tempera-tures.By activation at 700°C,a balance between pore making and self-healing is achieved in the final hard carbon.A large number of free radicals triggers rapid growth and aggregation of carbon microcrys-tals,blocking pre-formed open micropores and creating additional interconnected closed pores in as-obtained hard carbons.As a result,the optimized carbon anode(LK-700-1300)delivers a high reversible capacity of 330.8 mA h g^(-1) at 0.03 A g^(-1),which is an increase of 86 mA h g^(-1) compared to the pristine lignin-derived carbon anode(L-700-1300),and exhibits a good rate performance(202.1 mA h g^(-1) at 1 A g^(-1)).This work provides a universal and effective guidance for tuning closed pores of hard carbons from otherprecursors.

A Broad Range Triboelectric Stiffness Sensor for Variable Inclusions Recognition

With the development of artificial intelligence,stiffness sensors are extensively utilized in various fields,and their integration with robots for automated palpation has gained significant attention.This study presents a broad range self-powered stiffness sensor based on the triboelectric nanogenerator(Stiff-TENG)for variable inclusions in soft objects detection.The Stiff-TENG employs a stacked structure comprising an indium tin oxide film,an elastic sponge,a fluorinated ethylene propylene film with a conductive ink electrode,and two acrylic pieces with a shielding layer.Through the decoupling method,the Stiff-TENG achieves stiffness detection of objects within 1.0 s.The output performance and characteristics of the TENG for different stiffness objects under 4 mm displacement are analyzed.The Stiff-TENG is successfully used to detect the heterogeneous stiffness structures,enabling effective recognition of variable inclusions in soft object,reaching a recognition accuracy of 99.7%.Furthermore,its adaptability makes it well-suited for the detection of pathological conditions within the human body,as pathological tissues often exhibit changes in the stiffness of internal organs.This research highlights the innovative applications of TENG and thereby showcases its immense potential in healthcare applications such as palpation which assesses pathological conditions based on organ stiffness.

Geochemistry,Fluid Inclusions and Sulfur Isotopes of the Goshgarchay Cu-Au Deposit(Western Azerbaijan)in Lesser Caucasus:Implications for the Origins of Ore-forming Fluids

The Goshgarchay Cu-Au deposit is located in the central part of the northwest flank of the Murovdagh region in the Lesser Caucasus.The Goshgarchay Cu-Au deposit is associated with Middle Jurassic volcanic and Late Jurassic-Early Cretaceous high-K calc-alkaline intrusive rocks.The Cu-Au mineralization is commonly related to quartz-sericite-chlorite alteration dominantly composed of chalcopyrite,gold,sphalerite,pyrite,bornite,hematite,covellite,chalcocite,malachite,and azurite.The Goshgarchay copper-gold deposit,which is 600 m wide and approximately 1.2 km long,is seen as a faultcontrolled and vein-,stockwork-and disseminated type deposit.The Goshgarchay Cu-Au deposit predominantly comprises Cu(max.64500 ppm)and Au(max.11.3 ppm),while it comprises relatively less amounts Zn(max.437 ppm),Mo(max.47.5 ppm),Pb(max.134 ppm),and Ag(max.21 ppm).The homogenization temperatures and salinities of fluid inclusions in quartz for stage Ⅰ range from 380℃ to 327℃,and 6.9 wt% to 2.6 wt% NaCl eq.,respectively.Thand salinities in quartz for stage Ⅱ range from 304℃ to 253℃,and 7.6 wt% to 3.2 wt% NaCl eq.,respectively.The calculated δ^(34)S_(h2s)values(-1.5‰ to 5.5‰)of sulfides and especially the narrow range of δ^(34)S_(h2s) values of chalcopyrite and bornite(between -0.07‰ and +0.7‰)indicate that the source of the Goshgarchay Cu-Au mineralization is magmatic.Based on the mineralogical,geochemical,fluid inclusion,and sulfur isotopic data,the Goshgarchay Cu-Au deposit represents a late stage peripheral magmatic-hydrothermal mineralization probably underlain by a concealed porphyry deposit.

Modeling time-dependent mechanical behavior of hard rock considering excavation-induced damage and complex 3D stress states

To investigate the long-term stability of deep rocks,a three-dimensional(3D)time-dependent model that accounts for excavation-induced damage and complex stress state is developed.This model comprises three main components:a 3D viscoplastic isotropic constitutive relation that considers excavation damage and complex stress state,a quantitative relationship between critical irreversible deformation and complex stress state,and evolution characteristics of strength parameters.The proposed model is implemented in a self-developed numerical code,i.e.CASRock.The reliability of the model is validated through experiments.It is indicated that the time-dependent fracturing potential index(xTFPI)at a given time during the attenuation creep stage shows a negative correlation with the extent of excavationinduced damage.The time-dependent fracturing process of rock demonstrates a distinct interval effect of the intermediate principal stress,thereby highlighting the 3D stress-dependent characteristic of the model.Finally,the influence of excavation-induced damage and intermediate principal stress on the time-dependent fracturing characteristics of the surrounding rocks around the tunnel is discussed.

Geochemical characteristics of temperature and pressure of Paleozoic reservoir fluid inclusions in Xuanjing region, Lower Yangtze area

In order to understand the geochemical characteristics of Paleozoic reservoir fluids in Xuanjing region,Lower Yangtze area,drilling core samples from Y and D wells were tested and analyzed to study the fluid inclusion types and composition.Pressure correction was undertaken to determine the temperature and pressure environment for inclusion formation,and the influence of fluid characteristics of the Upper Permian and Lower Triassic reservoirs on the preservation of shale gas was investigated.According to petrograph-ic observations,fluid inclusions are mainly brine and bitumen inclusions.Bitumen inclusions are mainly distributed in holes and fractures,and with smaller individuals.No visible fluorescence was observed,and the vitrinite reflectance is 3.39%–3.92%.This indicates that there had been oil and gas accumulation in the early stage of diagenesis in the study area,but due to the influence of magmatic hydrothermal solution,oil and gas underwent thermal metamorphism in the early stage,making liquid petroleum into solid bitumen.At present,oil and gas in the reservoir were largely formed in the late stage.During the continuous process in which shale was buried,light oil and gas were generated.Light oil and gas underwent magmatic and tectonic hydrothermal processes in some areas,resulting in high-temperature metamorphic cracking that formed dry gas.Moreover,nitrogen inclusions are found in fluid inclusions,forming metamorphic fluids caused by mag-matic hydrothermal activities.The study shows that Paleozoic reservoirs in Xuanjing area are characterized by self-generation and self-storage.Furthermore,the mechanism of shale gas accumulation is not only related to the buried hydrocarbon generation process of shale itself,but is also related to later magmatic activity and tectonic hydrothermal transformation.Therefore,preservation conditions are generally key factors of shale gas accumulation in this area.