摘要：
To improve the laser cleaning surface quality of rust layers in Q390 steel, a method of determining the optimal cleaning parameters is proposed that is based on response surface methodology and the second-generation non-dominated sorting genetic algorithm (NSGA-II). It involves constructing a mathematical model of the input variables (laser power, cleaning speed, scanning speed, and repetition frequency) and the objective values (surface oxygen content, rust layer removal rate, and surface roughness). The effects of the laser cleaning process parameters on the cleaning surface quality were analyzed in our study, and accordingly, NSGA-II was used to determine the optimal process parameters. The results indicate that the optimal process parameters are as follows: a laser power of 44.99 W, cleaning speed of 174.01 mm/min, scanning speed of 3852.03 mm/s, and repetition frequency of 116 kHz. With these parameters, the surface corrosion is effectively removed, revealing a distinct metal luster and meeting the standard for surface treatment before welding.
通讯机构：
[He, HY; Wang, XL ] U;[He, HY ] Y;Univ South China, Sch Nucl Sci & Technol, Hengyang, Hunan, Peoples R China.;Univ South China, Coll Mech Engn, Hunan Prov Key Lab Ultrafast Micro Nano Technol &, Hengyang, Hunan, Peoples R China.;Yangtze Univ, Sch Elect Informat & Elect Engn, Jingzhou, Peoples R China.
摘要：
Four-layer hexagonal silicon carbide (4H-SiC) is a promising material for high-temperature and radiation-rich environments due to its excellent thermal conductivity and radiation resistance. However, real 4H-SiC crystals often contain Shockley-type stacking faults (SSF), which can affect their radiation resistance. This study employed molecular dynamics (MD) simulation method to explore the effects of SSF on radiation displacement cascades in 4H-SiC. We conducted a comprehensive study of various SSF within the crystalline framework of 4H-SiC, and analyzed their stacking fault energy (SFE). We simulated the radiation displacement cascade in 4H-SiC with SSF and analyzed the effects of SSF on the distribution of radiation displacement defects. We simulated the radiation displacement cascade in 4H-SiC with SSF under different energies of primary knock-on atom (EPKA) and temperatures (T) conditions, and analyzed the variation pattern of the number of radiation displacement defects and clusters. The results indicated that SSF limits defect distribution position. SSF has an effect on the defects and clusters of 4H-SiC in the displacement cascade, and SSF can affect the maximum working temperature of 4H-SiC. Four-layer hexagonal silicon carbide (4H-SiC) is a promising material for high-temperature and radiation-rich environments due to its excellent thermal conductivity and radiation resistance. Shockley-type stacking faults serve as one of the factors influencing the radiation resistance of 4H-SiC.
期刊：
Journal of Radioanalytical and Nuclear Chemistry,2024年333(5):2263-2271 ISSN：0236-5731
通讯作者：
Liu, L
作者机构：
[Yu, Shiwei; Liu, Lie; Ling, Ke; Liu, L] Univ South China, Sch Elect Engn, Hengyang 421000, Peoples R China.;[Liu, Lie; Zhang, Junze; Han, Lianghua; Liu, L] Univ South China, Sch Mech Engn, Hengyang 421000, Peoples R China.
通讯机构：
[Liu, L ] U;Univ South China, Sch Elect Engn, Hengyang 421000, Peoples R China.;Univ South China, Sch Mech Engn, Hengyang 421000, Peoples R China.
期刊：
Energy & Fuels,2024年38(8):7359-7367 ISSN：0887-0624
通讯作者：
Xitang Qian
作者机构：
[Qian, Xitang] Department of Chemical and Biological Engineering, the Hong Kong University of Science and Technology, Kowloon 87P7+X9, Hong Kong, P. R. China;[Huang, Chenhui; Zhang, Meng; Li, Dongliang; Kang, Xiaoming] College of Mechanical Engineering, University of South China, Hengyang 421001, P. R. China
通讯机构：
[Xitang Qian] D;Department of Chemical and Biological Engineering, the Hong Kong University of Science and Technology, Kowloon 87P7+X9, Hong Kong, P. R. China
摘要：
Cost-effective and versatile poly (ethylene oxide) (PEO)-based electrolytes have been a viable option within solid-state battery application systems due to their exceptional salt solvation capability and compatibility with electrode interfaces. However, the restricted lithium-ion mobility under standard temperature conditions and the formation of lithium dendrites pose substantial impediments to their application in high-capacity lithium metal batteries. To tackle this challenge, a thermally and mechanically robust solid-state electrolyte composite incorporating lithium-doped cobalt titanium oxide (LCTO) and PEO has been used. This electrolyte exhibits an extended electrochemical window of 5 V versus Li+/Li and a notable lithium-ion transference number. The presence of surface hydroxyl groups on the LCTO particles eliminates the interplay between lithium ions and anions in the lithium salt while simultaneously reducing the crystallinity of the PEO electrolyte and forming a three-dimensional lithium-ion pathway, ultimately leading to an enhanced lithium-ion conductivity of 0.85 mS cm–1 at 60 °C. The lithium symmetrical cell with LCTO-incorporated electrolyte demonstrates outstanding cycling (over 750 h under 0.1 mA cm–2). Additionally, LCTO-composite electrolyte-based LiFePO4 batteries exhibit excellent Coulombic efficiencies (>99.8%), low overpotentials (91.5 mV on average), and good cycling stability (120 cycles) at 60 °C.
期刊：
Physica Status Solidi-Rapid Research Letters,2024年18(2):2300334- ISSN：1862-6254
通讯作者：
Huo, SY
作者机构：
[Fu, Chun-Ming; Li, Hong-Kang; Huo, Shao-Yong; Yao, Long-Chao] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Huo, SY ] U;Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.
关键词：
defect states;elastic valley edge states;power dividers;rainbow trapping;topological phononic crystals
摘要：
Topological phononic crystals (PnCs) with topologically protected boundary states have important applications in the fields of acoustic wave transmission and control. However, previous studies based on solid-state PnC systems are mostly limited by fixed structures, resulting in the difficulty to deform the edge states, which partly limits its practical applications. Herein, a 2D solid topological PnC coupled with the defect is designed to achieve the adjustable valley edge state and rainbow trapping. First, by breaking the spatial inversion symmetry, the valley Hall phase transition of elastic wave is realized and valley edge states are obtained. Next, by introducing defects of different widths between the two different valleys' topological PnCs, both the defect-adjusted valley edge state and defect state are achieved. Then, by designing different topological PnCs waveguides, the robust transport characteristics of the two above states are compared. Subsequently, a new power divider based on the defect-adjusted valley edge state is designed, which is found to possess various manners of operation such as equal and unequal power divisions. Finally, based on defect adjustment of the edge states, a rainbow trapping is implemented. This research provides an important guidance for ultrasonic devices, such as waveguides, energy harvesters, and power dividers. By introducing the line defects in the topological domain wall for the elastic wave, the defect-adjusted valley edge states and defect states are presented, which further are applied to design the novel elastic ultrasonic devices, such as the equal or unequal power dividers and the rainbow trapping effects.image & COPY; 2023 WILEY-VCH GmbH
期刊：
Journal of Materials Chemistry A,2024年12(6):3331-3339 ISSN：2050-7488
通讯作者：
Ju, J;Qian, XT
作者机构：
[Huang, Chenhui; Kang, Xiaomin; Zhang, Meng] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Zhai, Zhaofeng] Chinese Acad Sci, Inst Met Res, Shenyang 110012, Peoples R China.;[Ju, Jiang] City Univ Hong Kong, Ctr Adv Nucl Safety & Sustainable Dev, Hong Kong 999077, Peoples R China.;[Qian, Xitang; Qian, XT] Hong Kong Univ Sci & Technol, Dept Chem & Biol Engn, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Qian, XT ] H;[Ju, J ] C;City Univ Hong Kong, Ctr Adv Nucl Safety & Sustainable Dev, Hong Kong 999077, Peoples R China.;Hong Kong Univ Sci & Technol, Dept Chem & Biol Engn, Kowloon, Hong Kong, Peoples R China.
摘要：
Nanofluidic ion regulation membranes have emerged as versatile platforms for applications in molecular/ion separation and energy conversion. The use of two-dimensional (2D) material-based membranes holds great potential for the regulation of nanofluidic ions owing to their unique properties of surface charges, nanochannels, and nanocapillary force. Herein, a class of 2D flexible ion-conductive membranes with surface charge-controllable and voltage-tunable ion transport properties, which are assembled with monolayered Cd vacancy-containing CdPS3 (vc-CdPS3)-based nanosheets, is reported. Importantly, the ion conductivity of the vc-CdPS3 membrane is several orders of magnitude higher than that of bulk salt solutions up to 0.1 M and reaches a plateau of similar to 10 mS cm(-1) in low concentrated solution (<= 1 mM), demonstrating typical charge-controllable nanofluidic ion transport behavior. This membrane exhibits excellent stability and maintains an ion conductivity of 23 and 20 mS cm(-1) under harsh acidic and alkaline conditions, respectively. By applying positive/negative gating voltage, ion transportation within the vc-CdPS3 membrane is tuned, resulting in low/high ion conductivity. The voltage-tunable behavior across a broad spectrum of cations with varying sizes and charges is observed, showcasing the ion-specific switch ratios of 12 and 10 for potassium and sodium ions, respectively, under an applied voltage of 2 V/-2 V. This work demonstrates the potential of vacancy-containing membranes for a variety of membrane separation applications and offer a strategy for preparing efficient ion transport devices.
摘要：
A 3D elastic-plastic FE model for simulating the force controlled stretch-bending process of double-cavity aluminum profile was established using hybrid explicit-implicit solvent method. Considering the computational accuracy and efficiency, the optimal choices of numerical parameters and algorithms in FE modelling were determined. The formation mechanisms of cross-section distortion and springback were revealed. The effects of pre-stretching, post-stretching, friction, and the addition of internal fillers on forming quality were investigated. The results show that the stress state of profile in stretch-bending is uniaxial with only a circumferential stress. The stress distribution along the length direction of profile is non-uniform and the maximum tensile stress is located at a certain distance away from the center of profile. As aluminum profile is gradually attached to bending die, the distribution characteristic of cross-section distortion along the length direction of profile changes from V-shape to W-shape. After unloading the forming tools, cross-section distortion decreases obviously due to the stress relaxation, with a maximum distortion difference of 13% before and after unloading. As pre-stretching and post-stretching forces increase, cross-section distortion increases gradually, while springback first decreases and then remains unchanged. With increasing friction between bending die and profile, cross-section distortion slightly decreases, while springback increases. Cross-section distortion decreases by 83% with adding PVC fillers into the cavities of profile, while springback increases by 192.2%.
通讯机构：
[Li, ZY ] U;Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.
关键词：
conductivity;conformation of PEDOT;organic photovoltaics;transmittance;work function
摘要：
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is widely utilized as the hole transport layer (HTL) inorganic photovoltaics (OPVs) because of its low-temperature solution processing peculiarity, high optical transmittance, and excellent mechanical flexibility. However, the core-shell structure of PSS coated PEDOT results in relatively low conductivity, work function, transmittance and waterproofness of PEDOT:PSS interlayer, limiting the photovoltaic performance and stability of OPVs. Here, the conformation of PEDOT chains are regulated from helical benzoyl to linear quinone structure via incorporation of 2D Cd(0.85)PS(3)Li(0.15)H(0.15)dopant into the conventional PEDOT:PSS interlayer, promoting an interpenetrating network structure in PEDOT:PSS interlayer and forming an efficient hole transport channel from active layer to ITO electrode. Such features significantly improve the electrical conductivity, work function, and transmittance of PEDOT:PSS interlayer. In consequence, the maximum power conversion efficiency (PCE) of D18:L8-BO, PBDB-T:ITIC, as well as PTzBI-dF:L8-BO based OPVs ameliorated from 18.37%, 8.94%, and 15.80% to 19.26%, 10.00%, and 16.83%, respectively. The application of Cd(0.85)PS(3)Li(0.15)H(0.15) doping PEDOT:PSS strategy demonstrates great potential for the development of strongly conductive, large-work-function, highly transparent, and excellent-waterproof PEDOT:PSS interlayer toward highly efficient and stable OPVs.
摘要：
An innovative MnO/Ti3C2 MXene heterostructure, consisting of three-dimensional (3D) MnO nanosheet array directly assembled on two-dimensional (2D) Ti3C2 MXene nanosheets, was synthesized via a simple hydrothermal-annealing strategy for uranium elimination. This unique 3D/2D heterostructure derived substantially high specific surface area (311.9 m2/g) and exposed considerable amount of surface oxygen groups, including surface lattice M-O and adsorbed -OH. Through a comprehensive exploration encompassing adsorbent dosage, pH, ionic strength, initial U(VI) concentration, and environmental conditions, the MnO/Ti3C2 MXene heterostructure demonstrated an extraordinary proficiency and specificity in the removal of U(VI). This composite exhibited an outstanding adsorption capacity of 862.1 mg/g, with a removal efficiency of 99.7 % and rapid kinetics (above 90 % within 20 s). The kinetic study indicated the adsorption process followed chemisorption dynamics and single -layer adsorption behavior. Comprehensive analyses validated the structural integrity and confirmed the successful uranium adsorption via strong interaction between UO22+ and surface unsaturated oxygen groups. Notably, the MnO/Ti3C2 MXene maintained excellent recyclability, highlighting its potential for large-scale applications. It emerges as a promising candidate for uranium removal, offering insights for optimizing composite materials in diverse environmental conditions and fostering advancements in water purification technologies.
摘要：
Surface structuring has attracted growing interest in the industry due to its potential to improve the macroscopic properties of workpieces. This work investigated the surface structuring of metals by combining thermal oxide film mask and laser lithography with isotropic etching. The metals were thermally oxidized to form a protective oxide film, laser ablation patterned the thermal oxide film, while electrochemical etching operated in the isotropic mode obtained an array of hemispherical cavities. The isotropic etching potential for different metals is taken from the mass transport region of the polarization curve. The effects of thermal oxide film thickness and laser ablation area on the uniformity of the etching holes were studied. The thermal oxidation of TA2 at 350 degrees C formed a 20-nm-thick oxide film, while an array of 10 mu m radius hemispherical microcavities was fabricated on the laser patterning surface via electrochemical etching at 2 V for 1 min. The surface structuring of stainless steel, pure nickel, and tungsten is highly dependent on the ability of the oxide film to avoid electrochemical reactions. The feasibility of combining thermal oxidation and laser lithography with electrochemical etching is of great value for the surface structuring of metallic materials for biomedical and microsystem applications.
摘要：
In this paper, a 3D multiphase flow model has been established for the plasma transferred arc (PTA) cladding of composite powder (NiCrBSi/50 wt% WC) on a 40CrNi2MoA substrate. The multiphase flow model simulates both the discrete phase (WC particles) and continuous phase in the melt pool, including the behaviors of heat transfer and particle distribution. The buoyancy, arc pressure, surface tension, and electromagnetic force are calculated. The model is then used to predict the influences of welding currents and preheating temperatures on the depth of heat-affected zone (HAZ), the temperature field, and the dimensions of the cladding layers. To validate this model, the dimensions and the HAZ depth are analyzed and compared to experimental data. The results show that the dimensions and HAZ depth obtained by the model simulation are in good agreement with the experiment. The HAZ depth, the melt pool length, and the dimensions of cladding layer would increase with the increasing welding current or preheating temperature. Driven by the inward convection in the melt pool, WC particles tend to distribute around the center line of cladding layers. This is the first work of modeling 3D multiphase flow in PTA cladding process of particle-reinforced metal matrix composite (MMCs). The work can provide theoretical guidance for adjusting process parameters to control HAZ depth and cladding quality in actual production.
In this paper, a 3D multiphase flow model has been established for the plasma transferred arc (PTA) cladding of composite powder (NiCrBSi/50 wt% WC) on a 40CrNi2MoA substrate. The multiphase flow model simulates both the discrete phase (WC particles) and continuous phase in the melt pool, including the behaviors of heat transfer and particle distribution. The buoyancy, arc pressure, surface tension, and electromagnetic force are calculated. The model is then used to predict the influences of welding currents and preheating temperatures on the depth of heat-affected zone (HAZ), the temperature field, and the dimensions of the cladding layers. To validate this model, the dimensions and the HAZ depth are analyzed and compared to experimental data. The results show that the dimensions and HAZ depth obtained by the model simulation are in good agreement with the experiment. The HAZ depth, the melt pool length, and the dimensions of cladding layer would increase with the increasing welding current or preheating temperature. Driven by the inward convection in the melt pool, WC particles tend to distribute around the center line of cladding layers. This is the first work of modeling 3D multiphase flow in PTA cladding process of particle-reinforced metal matrix composite (MMCs). The work can provide theoretical guidance for adjusting process parameters to control HAZ depth and cladding quality in actual production.
关键词：
Ti alloys;surface nitriding;microhardness;wear resistance;high-temperature oxidation resistance
摘要：
<jats:p>Titanium alloys are considered lightweight alloys and are widely applied across various industries. However, their low hardness, poor wear resistance, and limited oxidation resistance restrict their prospects for wider application. In this paper, nitride coatings were prepared using three preparation processes, namely laser surface nitriding (LSN), physical vapor deposition (PVD), and plasma ion implantation (PII). Their microstructure, microhardness, tribological behavior, and high-temperature oxidation characteristics were compared. The experimental results revealed that nitrided coatings were successfully prepared using the three methods. However, a comparison of these data shows that the LSN coating exhibited superior comprehensive performance. It achieved the maximum thickness within the shortest preparation time: the thickness was about 280 μm and the deposition rate of the LSN method was 2250 and 90,000 times higher than those of the PVD and PII methods. Nitrides have high hardness, but the carrying capacity could be attributed to the thickness of the coatings: the PVD coating could withstand a force of 500 g, while the PII coating only withstood a force of less than 25 g. In addition, as hardness is the most important factor for excellent wear resistance, the average volumetric wear rate of the LSN and PVD coatings was about 9 × 10−6 mm3/m·N, and their relative wear resistance was 49.2 times that of Ti6Al4V. Meanwhile, the excellent bond between the LSN coating and the substrate was evidenced by a high-temperature oxidation test during a rapid heating–cooling cycle.</jats:p>
作者机构：
[Lin, Yinghua; Wang, Xinlin; Lin, YH; Liu, Lipei] Univ South China, Coll Mech Engn, Hunan Prov Key Lab Ultrafast Micronano Technol & A, Hengyang 421001, Peoples R China.;[Peng, Longsheng] Hunan Lifang Roller Co Ltd, Hengyang 421681, Peoples R China.;[Peng, Longsheng] Hunan Adv Mfg Engn Technol Res Ctr High Wear Resis, Hengyang 421681, Peoples R China.;[Kang, Xin; Kang, X] Putian Univ, Sch Mech Elect & Informat Engn, Putian 351100, Peoples R China.
通讯机构：
[Kang, X ] P;[Lin, YH ] U;Univ South China, Coll Mech Engn, Hunan Prov Key Lab Ultrafast Micronano Technol & A, Hengyang 421001, Peoples R China.;Putian Univ, Sch Mech Elect & Informat Engn, Putian 351100, Peoples R China.
关键词：
laser cladding;surface strengthening;Fe-based alloy;high hardness;microstructure design and control
摘要：
High-hardness iron-based alloy coatings are extensively utilized in aerospace, automotive, and industrial equipment due to their exceptional wear resistance and long service life. Laser cladding has emerged as one of the primary techniques for fabricating these coatings, owing to its rapid cooling and dense microstructure characteristics. However, the production of high-hardness iron-based alloy coatings via laser cladding continues to face numerous challenges, particularly when controlling the morphology, quantity, and distribution of the reinforcing phases, which can lead to cracking during processing and service, thus compromising their usability. The cracks of the cladding layer will be suppressed through good microstructure design and control, resulting in a wide range of performance for high-hardness Fe-based alloy coatings. This paper reviews recent advancements in the design and control of the organization and structure of high-hardness iron-based alloy coatings from the perspectives of material composition, processing parameters, and external assistance techniques. It summarizes the properties and applications of various materials, including different alloying elements, ceramic particles, and rare earth oxides, while systematically discussing how processing parameters influence microstructure and performance. Additionally, the mechanisms by which external auxiliary energy fields affect the melt pool and solidified microstructure during laser cladding are elucidated. Finally, the future development directions of laser cladding technology for high-hardness iron-based coatings are anticipated, emphasizing the need for further quantification of the optimal coupling relationships among the gain effects of composite energy fields.
作者机构：
[唐鹏; 唐虎; 易礼杨; 李必文] School of Mechanical Engineering, University of South China, Hengyang 421001, Hunan, China;[谭文甫] Department of Orthopaedics Trauma, the Second Affiliated Hospital of University of South China, Hengyang 421001, Hunan, China
摘要：
Parallel infill sampling is a promising approach to improve the efficiency of multi-fidelity multi-objective Bayesian optimization (MOBO). In existing literature, the number of infill samples per iteration is typically limited to 10. Additionally, the application of the multi-fidelity MOBO method in engineering optimization designs with over 100 variables is rare. To that end, a novel generalized expected improvement matrix (GEIM) criterion is proposed by using generalized reference values for the element in expected improvement matrix. Parallel infill sampling strategy based on GEIM is developed and incorporated into the multi-fidelity MOBO framework. The distinct feature of the proposed method is that the number of infill samples at each iteration can be significantly larger than existing methods (i.e. as much as 100), so as to further enhance the optimization efficiency. Empirical experiment results on analytic problems show that the proposed parallel multi-fidelity MOBO method is highly competitive in comparison with existing methods. To address the curse of dimensionality in optimizing multi-stage axial compressor, an efficient modeling method for the Hierarchical Kriging (HK) is incorporated. The HK predictor for the efficiency of the 3-stage compressor with 144 variables is built in 16.71 s with acceptable accuracy. Remarkable improvements over the two objectives of the 3-stage compressor with 144 variables are achieved simultaneously within 870 high-fidelity CFD simulations.
作者机构：
[Dewen Tang] School of Mechanical Engineering, University of South China, Hengyang, China;Spallation Neutron Source Science Center, Dongguan, China;[Quan Ji] Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China;[Chang Shu] School of Mechanical Engineering, University of South China, Hengyang, China<&wdkj&>Spallation Neutron Source Science Center, Dongguan, China;[Junsong Zhang] Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China<&wdkj&>Spallation Neutron Source Science Center, Dongguan, China
通讯机构：
[Junsong Zhang] I;Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China<&wdkj&>Spallation Neutron Source Science Center, Dongguan, China
摘要：
Design the sextupole precision mover for the Southern Advanced Photon Source that has requirements exceeding commercially available machines. The design of the mover has been verified to meet the requirements through a combination of static and dynamic simulations using ANSYS software, as well as relevant experimental testing. The mover we constructed has an absolute positioning error of 2 and 3 µm, a maximum inclination angle of 1.55″ and 5.67″ in the horizontal and vertical motion directions respectively under a 400 kg load. Its vibration force transmission rate is 1.065. The mover utilizes a non-coupled structure consisting of four layers of stainless steel plates, which exhibits good manufacturability. It is capable of achieving high precision and stability under a 400 kg load, meeting the requirements.
