Subjects -> MINES AND MINING INDUSTRY (Total: 82 journals)
Showing 1 - 42 of 42 Journals sorted by number of followers
Stainless Steel World     Full-text available via subscription   (Followers: 18)
Journal of Applied Geophysics     Hybrid Journal   (Followers: 16)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 15)
International Journal of Hospitality & Tourism Administration     Hybrid Journal   (Followers: 14)
European Journal of Mineralogy     Hybrid Journal   (Followers: 12)
Journal of Geology and Mining Research     Open Access   (Followers: 11)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 11)
Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 11)
Transactions of Nonferrous Metals Society of China     Hybrid Journal   (Followers: 10)
Journal of Human Resources in Hospitality & Tourism     Hybrid Journal   (Followers: 9)
Clay Minerals     Hybrid Journal   (Followers: 9)
Minerals Engineering     Hybrid Journal   (Followers: 9)
Lithos     Hybrid Journal   (Followers: 9)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 9)
Natural Resources Research     Hybrid Journal   (Followers: 8)
Geotechnical and Geological Engineering     Hybrid Journal   (Followers: 8)
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 7)
International Journal of Rock Mechanics and Mining Sciences     Hybrid Journal   (Followers: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
International Journal of Mining Engineering and Mineral Processing     Open Access   (Followers: 5)
Journal of Quality Assurance in Hospitality & Tourism     Hybrid Journal   (Followers: 5)
Mine Water and the Environment     Hybrid Journal   (Followers: 5)
International Journal of Mining and Mineral Engineering     Hybrid Journal   (Followers: 5)
Journal of the Southern African Institute of Mining and Metallurgy     Open Access   (Followers: 5)
Mining Engineering     Full-text available via subscription   (Followers: 5)
Resources Policy     Hybrid Journal   (Followers: 4)
International Journal of Mining Science and Technology     Open Access   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 4)
Mineral Processing and Extractive Metallurgy Review     Hybrid Journal   (Followers: 4)
Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 4)
International Journal of Coal Geology     Hybrid Journal   (Followers: 4)
Physics and Chemistry of Minerals     Hybrid Journal   (Followers: 4)
Journal of Convention & Event Tourism     Hybrid Journal   (Followers: 4)
Mineralium Deposita     Hybrid Journal   (Followers: 4)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 3)
Journal of Sustainable Mining     Open Access   (Followers: 3)
International Journal of Coal Science & Technology     Open Access   (Followers: 3)
Mining Journal     Full-text available via subscription   (Followers: 3)
Ghana Mining Journal     Full-text available via subscription   (Followers: 3)
Geology of Ore Deposits     Hybrid Journal   (Followers: 3)
Rocks & Minerals     Hybrid Journal   (Followers: 3)
Environmental Geochemistry and Health     Hybrid Journal   (Followers: 2)
Journal of Mining Science     Hybrid Journal   (Followers: 2)
Geomaterials     Open Access   (Followers: 2)
Mineralogia     Open Access   (Followers: 2)
BHM Berg- und Hüttenmännische Monatshefte     Hybrid Journal   (Followers: 2)
Mining Technology : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 2)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
International Journal of Coal Preparation and Utilization     Hybrid Journal   (Followers: 2)
Mineralogy and Petrology     Hybrid Journal   (Followers: 2)
Mining Report     Hybrid Journal   (Followers: 2)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 2)
Archives of Mining Sciences     Open Access   (Followers: 2)
Journal of Materials Research and Technology     Open Access   (Followers: 2)
Gems & Gemology     Full-text available via subscription   (Followers: 1)
Journal of Analytical and Numerical Methods in Mining Engineering     Open Access   (Followers: 1)
Rangeland Journal     Hybrid Journal   (Followers: 1)
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access   (Followers: 1)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Mineralogical Magazine     Hybrid Journal   (Followers: 1)
CIM Journal     Hybrid Journal  
Natural Resources & Engineering     Hybrid Journal  
Mining, Metallurgy & Exploration     Hybrid Journal  
Podzemni Radovi     Open Access  
Rudarsko-geološko-naftni Zbornik     Open Access  
Journal of Mining Institute     Open Access  
International Journal of Mining and Geo-Engineering     Open Access  
Journal of China Coal Society     Open Access  
Réalités industrielles     Full-text available via subscription  
Mineral Economics     Hybrid Journal  
Minerals     Open Access  
Gold Bulletin     Hybrid Journal  
Minerals & Energy - Raw Materials Report     Hybrid Journal  
Similar Journals
Journal Cover
Journal of Central South University
Journal Prestige (SJR): 0.336
Citation Impact (citeScore): 1
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2095-2899 - ISSN (Online) 2227-5223
Published by Springer-Verlag Homepage  [2469 journals]
  • Forming Proterozoic basement within eastern Central Asian Orogenic Belt:
           Evidence from zircon U-Pb-Hf-O isotopes

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      Abstract: Abstract As part of the mosaic of micro-continents within the Central Asian Orogenic Belt (CAOB), the Xing’an-Airgin Sum Block (XAB) features increasingly-recognized Meso-Neoproterozoic geological records. However, the origin, temporal-spatial distribution of ancient materials, and their roles in crust evolution remain to debate. This paper presents an integrated study of zircon U-Pb ages and Hf-O isotopes for Mesoproterozoic and Paleozoic granites from the Erenhot region of central Inner Mongolia, along eastern CAOB. The intrusion of 1450 Ma syenogranite denotes that the Precambrian basement of XAB extends from Sonid Zuoqi westward to Erenhot. The 384 and 281 Ma monzogranites containing Mesoproterozoic xenocrystic zircons possess Proterozoic-dominant two-stage Hf model ages, further suggesting the wide existence of Proterozoic crust beneath western XAB. Cyclic Proterozoic crustal growth and reworking seem to show close linkages with the orogenesis during relevant supercontinent cycles. 1450–1360 Ma juvenile crustal growth at Erenhot and synchronous ancient crust reworking at Sonid Zuoqi and Abagaqi were likely resulted from retreating subduction involved in Columbia breakup, while 1.2–1.0 Ga reworking and 0.9–0.7 Ga growth events within the Erenhot basement might respond to assembly and breakup of Rodinia, respectively. Besides, our work confirms that reworking of Neoproterozoic crust played important roles during Paleozoic multi-stage accretion of CAOB.
      PubDate: 2022-07-23
       
  • Nonlinear free vibration of graphene platelets reinforced composite
           corrugated plates

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      Abstract: Abstract The nonlinear vibration of graphene platelets reinforced composite corrugated (GPRCC) rectangular plates with shallow trapezoidal corrugations is investigated. Since graphene platelets are prone to agglomeration, a multi-layer distribution is adopted here to match the engineering requirements. Firstly, an equivalent composite plate model is obtained, and then nonlinear equations of motion are derived by the von Kármán nonlinear geometric relationship and Hamilton’s principle. Afterwards, the Galerkin method and harmonic balance method are used to obtain an approximate analytical solution. Results show that the unit cell half period, unit cell inclination angle, unit cell height, graphene platelet dispersion pattern and graphene platelet weight fraction and geometry play important roles in the nonlinear vibration of the GPRCC plates.
      PubDate: 2022-07-11
       
  • La0.75Sr0.25Cr0.5Mn0.5O3−δ-Ce0.8Gd0.2O1.9 composite electrodes as
           anodes in LaGaO3-based direct carbon solid oxide fuel cells

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      Abstract: Abstract Direct carbon solid oxide fuel cells (DC-SOFCs) are promising, green, and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures. Developing and designing suitable anode materials for DC-SOFC is substantial scientific challenge. Herein we investigated the use of La0.75Sr0.25Cr0.5Mn0.5O3−δ—Ce0.8Gd0.2O1.9 (LSCM—GDC) composite electrodes as anodes for La0.9Sr0.1Ga0.8Mg0.2O3−δ electrolyte-based DC-SOFCs, with Camellia oleifera shell char as the carbon fuel The LSCM—GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm2 at 800 °C and it significantly improved to 425 mW/cm2 after Ni nanoparticles were introduced into the LSCM—GDC anode through wet impregnation The microstructures of the prepared anodes were characterized, and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied The above results indicate that LSCM—GDC anode is promising to be applied in DC-SOFCs.
      PubDate: 2022-06-22
       
  • Application of a novel detection approach based on non-dispersive infrared
           theory to the in-situ analysis on indicator gases from underground coal
           fire

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      Abstract: Abstract Coal mine fires, which can cause heavy casualties, environmental damages and a waste of coal resources, have become a worldwide problem. Aiming at overcoming the drawbacks, such as a low analysis efficiency, poor stability and large monitoring error, of the existing underground coal fire monitoring technology, a novel monitoring system based on non-dispersive infrared (NDIR) spectroscopy is developed. In this study, first, the measurement principle of NDIR sensor, the gas concentration calculation and its temperature compensation algorithms were expounded. Next, taking CO and CH4 as examples, the liner correlation coefficients of absorbance and the temperature correction factors of the two indicator gases were calculated, and then the errors of concentration measurement for CO, CO2, CH4 and C2H4 were further analyzed. The results disclose that the designed NDIR sensors can satisfy the requirements of industrial standards for monitoring the indicator gases for coal fire hazards. For the established NDIR-based monitoring system, the NDIR-based spectrum analyzer and its auxiliary equipment boast intrinsically safe and explosion-proof performances and can achieve real-time and in-situ detection of indicator gases when installed close to the coal fire risk area underground. Furthermore, a field application of the NDIR-based monitoring system in a coal mine shows that the NDIR-based spectrum analyzer has a permissible difference from the chromatography in measuring the concentrations of various indicator gases. Besides, the advantages of high accuracy, quick analysis and excellent security of the NDIR-based monitoring system have promoted its application in many coal mines.
      PubDate: 2022-06-03
       
  • Influence of thermal contact resistance on dynamic response of bilayered
           saturated porous strata

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      Abstract: Abstract Porous materials can be found in a variety of geophysical and engineering applications. The existence of thermal contact resistance at the interface between bilayered saturated porous strata would result in a significant temperature difference at the interface. An attempt is made to study the thermo-hydro-mechanical coupling dynamic response of bilayered saturated porous strata with thermal contact resistance and elastic wave impedance. The corresponding analytical solutions for the dynamic response of bilayered saturated porous strata under a harmonic thermal load are derived by the operator decomposition method, and their rationality is verified by comparing them with existing solutions. The influences of thermal contact resistance, thermal conductivity ratio, and porosity ratio on the dynamic response of bilayered saturated porous strata are systematically investigated. Outcomes disclose that with the increase of thermal contact resistance, the displacement, pore water pressure and stress decrease gradually, and the temperature jump at the interface between two saturated porous strata increases.
      PubDate: 2022-06-01
       
  • Siderite pyrolysis in suspension roasting: An in-situ study on kinetics,
           phase transformation, and product properties

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      Abstract: Abstract Siderite, as an abundant iron ore, has not been effectively utilized, with a low utilization rate. In this study, the in-situ kinetics and mechanism of siderite during suspension magnetization roasting (SMR) were investigated to improve the selective conversion of siderite to magnetite and CO, enriching the theoretical system of green SMR using siderite as a reductant. According to the gas products analyses, the peak value of the reaction rate increased with increasing temperature, and its curves presented the feature of an early peak and long tail. The mechanism function of the siderite pyrolysis was the contraction sphere model (R3): f(α) =3(1 − α)2/3; Eα was 46.4653 kJ/mol; A was 0.5938 s−1; the kinetics equation was k=0.5938exp[− 46.4653/(RT)]. The in-situ HT-XRD results indicated that siderite was converted into magnetite and wüstite that exhibited a good crystallinity in SMR under a N2 atmosphere. At 620 °C, the saturation magnetization (Ms), remanence magnetization (Mr), and coercivity (Hc) of the product peaked at 53.63×10−3 A·m2/g, 10.23× 10−3A×m2/g, and 12.40×103 A/m, respectively. Meanwhile, the initial particles with a smooth surface were transformed into particles with a porous and loose structure in the roasting process, which would contribute to reducing the grinding cost.
      PubDate: 2022-06-01
       
  • Mechanical properties and microscopic failure process of exemplary
           argillaceous interlayer from east China

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      Abstract: Abstract The landslide disaster caused by the argillaceous interlayer not only destroys buildings, cultivated land, and roads but also seriously endangers human life and safety. This study concerns the mineral composition of selected argillaceous interlayer and their strength characteristics. To study the mineral composition of argillaceous interlayers, 8 kinds of samples in the southern Jiangsu region of China were analyzed utilizing X-ray diffraction (XRD). The repeated direct shear strength tests (RDST) were carried out on the undisturbed specimens of the argillaceous interlayer. The results show that the argillaceous interlayer with high content of kaolinite shows ductile failure mode, which means that there is no obvious residual strength in the shear process. The arrangement of mineral particles on the shear surface of the specimens after different shear displacements was observed under the scanning electron microscope (SEM). It was observed that mineral particles on the shear surface showed a more directional arrangement with the increase of shear displacement. Furthermore, the influence of shear direction on the argillaceous interlayer with completely oriented mineral particles was studied through numerical experiments with four shear strength mechanisms proposition proposed. The influence of the mineral arrangement on the action occasion and magnitude of dilatancy component of shear strength is clarified in the shear mechanism.
      PubDate: 2022-06-01
       
  • Feasibility of replacing the 3-coach with a 1.5-coach grouping train model
           in wind tunnel experiment at different yaw angles

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      Abstract: Abstract The effects of different yaw angles on the aerodynamic performance of city electric multiple units (EMUs) were investigated in a wind tunnel using a 1:16.8 scaled model. Pressure scanning valve and six-component box-type aerodynamic balance were used to test the pressure distribution and aerodynamic force of the head car respectively from the 1.5- and 3-coach grouping city EMU models. Meanwhile, the effects of the yaw angles on the pressure distribution of the streamlined head as well as the aerodynamic forces of the train were analyzed. The experimental results showed that the pressure coefficient was the smallest at the maximum slope of the main shape-line. The side force coefficient and pressure coefficient along the head car cross-section were most affected by crosswind when the yaw angle was 55°, and replacing a 3-coach grouping with a 1.5-coach grouping had obvious advantages for wind tunnel testing when the yaw angle was within 24.2°. In addition, the relative errors of lift coefficient CL, roll moment coefficient CMx, side force coefficient CS, and drag coefficient CD between the 1.5- and 3-coach cases were below 5.95%, which all met the requirements of the experimental accuracy.
      PubDate: 2022-06-01
       
  • Valorization of natural diatomite mineral: Application to removal of
           anionic dye from aqueous solution in a batch and fixed-bed reactor

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      Abstract: Abstract In this work, the efficiency of an adsorption process, in which Moroccan diatomite (ND) is used as a low-cost adsorbent to remove Congo red (CR) dye from contaminated waters in batch and column system, was examined. The influence of experimental conditions (pH, adsorbent dose and temperature) on the adsorption of CR onto the ND adsorbent was studied. A study of the adsorption kinetics for CR revealed that a pseudo-second-order model provided the best fit to the experimental kinetic data, and the equilibrium data were well described by the Langmuir isotherm model with an adsorption capacity of 6.07 mg/g using 15 g/L of ND, pH=6, contact time 3 h and 25 °C. On the other hand, the ND regeneration tests were investigated and showed that the desorption reaches at least 50% when using ethanol as eluent. In addition, the adsorption process in a continuous mode was studied. Breakthrough curves were properly represented by the Yoon — Nelson model. Hence, the adsorption capacity of 5.71 mg/g was reached using 0.114 g of adsorbent, CR concentration of 6 mg/L and a flow of 1 mL/min under 25 °C.
      PubDate: 2022-06-01
       
  • An analytical p-y curve method based on compressive soil pressure model in
           sand soil

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      Abstract: Abstract With the high-quality development of urban buildings, higher requirements are come up with for lateral bearing capacity of laterally loaded piles. Consequently, a more accurate analysis to predict the lateral response of the pile within an allowable displacement is an important issue. However, the current p-y curve methods cannot fully take into account the pile-soil interaction, which will lead to a large calculation difference. In this paper, a new analytical p-y curve is established and a finite difference method for determining the lateral response of pile is proposed, which can consider the separation effect of pile-soil interface and the coefficient of circumferential friction resistance. In particular, an analytical expression is developed to determine the compressive soil pressure by dividing the compressive soil pressure into two parts: initial compressive soil pressure and increment of compressive soil pressure. In addition, the relationship between compressive soil pressure and horizontal displacement of the pile is established based on the reasonable assumption. The correctness of the proposed method is verified through four examples. Based on the verified method, a parametric analysis is also conducted to investigate the influences of factors on lateral response of the pile, including internal friction angle, pile length and elastic modulus of pile.
      PubDate: 2022-06-01
       
  • Physical and mechanical properties of Beishan granite after different high
           temperature treatments

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      Abstract: Abstract In China, Beishan granite is chosen as a potential host surrounding rock of a high-level radioactive waste (HLW) repository. For this research, Beishan granite specimens were heated up to 300 °C, 400 °C and 500 °C, respectively. And conventional triaxial compression tests were conducted after cooling down the samples. The results show that after 300 °C, 400 °C and 500 °C heating treatment, the diameter of samples increases by 0.066%, 0.143% and 0.409%, respectively, which is a little larger than the axial length changes. Mechanical tests show that peak strength increases slightly with increasing temperature. However, the dilatancy threshold is lower than that observed for samples which have not experienced heating treatment. Peak strain and dilatancy threshold strain show a strong temperature dependence. The higher the temperature, the greater the strain. Furthermore, increasing temperature has negative influence on threshold elastic modulus Ec and tangent elastic modulus Et. Poisson ratio decreases when temperature increases from 300 °C to 500 °C, but it is still larger than that observed for samples which have not experienced heating treatment. In addition, AE monitoring shows a quiet period in the initial loading stage, which proves that the micro cracks are closed during heating and contribute to the increase of peak strength.
      PubDate: 2022-06-01
       
  • Kinetics of nitric acid leaching of low-grade rare earth elements from
           phosphogypsum

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      Abstract: Abstract Phosphogypsum (PG) is a potential resource for rare earth elements (REEs). Several studies have been carried out on REE leaching from PG. However, few in-depth studies have investigated the kinetics of this leaching process. In this study, the leaching kinetics of REEs from PG in nitric acid at different temperatures were explored in depth. The experiments show that the maximum leaching recovery for ς REE was 58.5%, 75.9% and 83.4% at 30, 60 and 80 °C, respectively. Additionally, among La, Ce, Y and Nd, Y had the highest leaching rate. A new shrinking core model (SCM) based on the dissolution reaction of a cylindrical solid particle with interfacial transfer and diffusion across the product layer as the rate-controlling step was deduced and could well fit the leaching process of REEs from PG. The activation energies for the leaching of La, Ce, Y and Nd were determined on the basis of the new cylindrical SCM. In summary, the cylindrical SCM was a more suitable fitting model than the spherical SCM, and the interfacial transfer and diffusion across the product layer were the rate-controlling step for REE leaching from the PG sample.
      PubDate: 2022-06-01
       
  • Mechanical properties of deep sandstones under loading rate effect

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      Abstract: Abstract The advance speed of the working face in coal mines can significantly affect the fluctuation frequency of abutment pressure in front of the coal body. Moreover, it has a certain correlation with the change of axial loading rate in coal and rock mechanics test. Therefore, uniaxial compression tests under various loading rates of 0.05, 0.1, 0.15, 0.25, 0.5 MPa/s were conducted using 2000 kN triaxial testing machine and PCI-2 acoustic emission test system to study the loading rate effect on the mechanical properties of deep sandstones. The results show that 1) the peak strength and elastic modulus of the deep sandstone increase with the loading rate increasing; 2) with the loading rate increasing, the deep sandstone transforms from plastic-elastic-plastic to plastic-elastic and moreover, the failure mode gradually transfers from type I to type III; 3) With the loading rate increasing, the total input strain energy, elastic strain energy, and dissipated strain energy generally increase; 4) the damage variable presents the evolution characteristics of inverted “S” shape with time, and with the loading rate increasing, the damage degree of the deep sandstone is aggravated. The conclusion obtained can provide the theoretical basis for the stability control of the surrounding rock in deep engineering.
      PubDate: 2022-06-01
       
  • An enhanced hybrid ensemble deep learning approach for forecasting daily
           PM2.5

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      Abstract: Abstract PM2.5 forecasting technology can provide a scientific and effective way to assist environmental governance and protect public health. To forecast PM2.5, an enhanced hybrid ensemble deep learning model is proposed in this research The whole framework of the proposed model can be generalized as follows: the original PM2.5 series is decomposed into 8 sub-series with different frequency characteristics by variational mode decomposition (VMD); the long short-term memory (LSTM) network, echo state network (ESN), and temporal convolutional network (TCN) are applied for parallel forecasting for 8 different frequency PM2.5 sub-series; the gradient boosting decision tree (GBDT) is applied to assemble and reconstruct the forecasting results of LSTM, ESN and TCN. By comparing the forecasting data of the models over 3 PM2.5 series collected from Shenyang, Changsha and Shenzhen, the conclusions can be drawn that GBDT is a more effective method to integrate the forecasting result than traditional heuristic algorithms; MAE values of the proposed model on 3 PM2.5 series are 1.587, 1.718 and 1.327 µg/m3, respectively and the proposed model achieves more accurate results for all experiments than sixteen alternative forecasting models which contain three state-of-the-art models.
      PubDate: 2022-06-01
       
  • Experimental study on mechanical properties of basalt fiber-reinforced
           silty clay

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      Abstract: Abstract Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering. Basalt fiber is a new kind of environment-friendly and high-performance soil reinforcement material, and the mechanical properties of basalt fiber-reinforced soil have become a hot research topic. In this paper, we conducted monotonic triaxial and cyclic triaxial tests, and analyzed the influence of the fiber content, moisture content, and confining pressure on the shear characteristics, dynamic modulus, and damping ratio of basalt fiber-reinforced silty clay. The results illustrate that basalt fiber can enhance the shear strength of silty clay by increasing its cohesion. We find that the shear strength of reinforced silty clay reaches its maximum when the fiber content is approximately 0.2% and the moisture content is 18.5% (optimum moisture content). Similarly, we also find that the dynamic modulus that corresponds to the same strain first increases then decreases with increasing fiber content and moisture content and reaches its maximum when the fiber content is approximately 0.2% and the moisture content is 18.5%. The dynamic modulus is positively correlated with the confining pressure. However, the change in the damping ratio with fiber content, moisture content, and confining pressure is opposite to that of the dynamic modulus. It can be concluded that the optimum content of basalt fiber for use in silty clay is 0.2%. After our experiments, we used scanning electron microscope (SEM) to observe the microstructure of specimens with different fiber contents, and our results show that the gripping effect and binding effect are the main mechanisms of fiber reinforcement.
      PubDate: 2022-06-01
       
  • A 3D graphene/polyimide fiber framework with improved thermal conductivity
           and mechanical performance

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      Abstract: Abstract The integration of electronic components and the popularity of flexible devices have come up with higher expectations for the heat dissipation capability and comprehensive mechanical performance of thermal management materials. In this work, after the modification of polyimide (PI) fibers through oxidation and amination, the obtained PDA@OPI fibers (polydopamine (PDA)-modified pre-oxidized PI fibers) with abundant amino groups were mixed into graphene oxide (GO) to form uniform GO-PDA@OPI composites. Followed by evaporation, carbonization, graphitization and mechanical compaction, the G-gPDA@OPI films with a stable three-dimensional (3D) long-range interconnected covalent structure were built. In particular, due to the rich covalent bonds between GO layers and PDI@OPI fibers, the enhanced synergistic graphitization promotes an ordered graphitized structure with less interlayer distance between adjacent graphene sheets in composite film. As a result, the optimized G-gPDA@OPI film displays an improved tensile strength of 78.5 MPa, tensile strain of 19.4% and thermal conductivity of 1028 W/(m·K). Simultaneously, it also shows superior flexibility and high resilience. This work provides an easily-controlled and relatively low-cost route for fabricating multifunctional graphene heat dissipation films.
      PubDate: 2022-06-01
       
  • Preparing low-oxygen Ti-6Al-4V alloy powder through direct reduction of
           oxides and its synergistic reaction mechanism

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      Abstract: Abstract Ti-6Al-4V alloy powder was prepared through a two-step reduction of a mixture of TiO2, V2O5 and Al2O3 in this study. The oxide mixture was first reduced by Mg in MgCl2 at 750 °C in argon, where oxygen was reduced to 2.47 wt% from 40.02 wt%. The oxygen content in the final powder was eventually reduced to an extremely low level (0.055 wt%) using calcium at 900 °C in argon, and the final powder had the composition of 90.12 wt% Ti, 5.57 wt% Al, and 3.87 wt% V, which meets the standard specification of Ti-6Al-4V (ASTM F1108-09). Between the two reductions, a heat treatment step was designed to help controlling the specific surface area and particle size. The effect of the heat treatment temperature on the morphology, and composition uniformity of the powder was investigated in detail. Heat treatment above 1300 °C attributed to a dense powder with a controlled specific surface area. Thermodynamic modeling and experimental results indicated that only α-Ti enriched with Al and β-Ti enriched with V exist in the final powder, and other possible phases including Al-Mg and Al-V were excluded. This study also offers a triple-step thermochemical process for producing high-purity Ti-based alloy powder.
      PubDate: 2022-06-01
       
  • Thermal-mechanical and springback behavior of dual-phase steel at warm
           temperatures

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      Abstract: Abstract for non-quenchable dual-phase (DP) steel sheet, the warm forming process can effectively reduce the amount of springback, and the mechanical parameters that influence its elastic and inelastic recovery to decrease exhibit a strong temperature dependence, especially under cyclic loading conditions. In this paper, the monotonic and cyclic loading tests of DP980 steel sheets are conducted at the temperatures ranging from 25 °C to 500 °C. The temperature-dependent flow stress, nonlinear elastic recovery, and Bauschinger effect are investigated. The results demonstrate that both the elastic modulus and Bauschinger effect show an exponential law with pre-strain, and decrease with the increase of forming temperature, while there will be an abnormal phenomenon of rebound due to the influence of dynamic strain aging effect. Meanwhile, a linear relationship between the Bauschinger effect and inelastic strain is observed at various temperatures, and the weight of the Bauschinger effect in the total strain reduces with temperature increasing, which indicates that the springback is dominated by linear elastic recovery. Furthermore, the U-draw bending tests are carried out to clarify the influence of Vickers hardness distribution and martensite size effect on the springback behavior.
      PubDate: 2022-06-01
       
  • Limit analysis of ultimate uplift capacity and failure mechanism of
           shallow plate anchors in multi-layered soils

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      Abstract: Abstract Considering the fact that in some complex cases, plate anchors are buried in multi-layered geotechnical materials, the ultimate dynamic analysis was performed to investigate the uplift capacity and failure mechanism of shallow strips and circular plate anchors in multi-layered soils. The nonlinear strength criterion and non-associated flow rule of geotechnical materials were introduced to investigate the influence of nonuniformity on the pullout performance and failure mechanism of shallow plate anchors. The expressions of the detaching curves or surfaces were obtained to reflect the failure mechanism, which can be used to figure out the ultimate uplift capacity and failure range. The results are generally in agreement with the numerical simulations and previous research. The effects of various parameters on the ultimate uplift capacity and failure mechanism of plate anchors in multi-layered soils were investigated, and it is found that the ultimate uplift capacity and failure range of shallow anchors increase with the increase of initial cohesion and dilatancy coefficient, but decrease with the unit weight, axial tensile stress and nonlinear coefficient.
      PubDate: 2022-06-01
       
  • Reduction and subsequent carburization of pre-oxidation magnetite pellets

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      Abstract: Abstract Magnetite is a kind of iron ore that is difficult to carburize. In order to improve the carburizing performance of magnetite pellet, pre-oxidation treatment was carried out, and the oxidation, reduction and carburization behaviors of magnetite pellet were investigated in this study. The magnetite pellet was oxidized in the air and carburized in CO-CO2-H2 gas mixtures, the oxidation, reduction and carburization behaviors were demonstrated by detecting phase change, microstructure, carburizing index via thermogravimetry, X-ray diffraction (XRD), infrared carbon-sulfur analyzer, and scanning electron microscope (SEM). The results show that the dense magnetite particles inside pellet are oxidized to porous hematite particles, and the Fe3O4 transforms to Fe2O3 with high lattice defect concentration during the pre-oxidation process. Then the porous hematite particles and newly formed Fe2O3 significantly promote the reduction efficiency. Porous metallic iron particles are produced in the reduction process. Finally, both high reduction efficiency and the porous structure of metallic iron particles dramatically enhance the carburization efficiency of pellet. High pre-oxidation temperature favors to the carburization of magnetite pellet. However, the carburized index decreases due to the recrystallization of iron oxide when the temperature extends to 1000 ° C. The optimum pre-oxidation temperature for magnetite pellet carburization is 900 °C.
      PubDate: 2022-06-01
       
 
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