- Ei，ESCI收录期刊
- 中国科学引文数据库(CSCD)核心期刊
- 中文核心期刊
- 文摘与引文数据库(Scopus)
- 剑桥科学文摘(CSA)
Hydrogel， a soft material composed of polymers with a three-dimensional network structure， has been widely used in fields such as environmental engineering and biomedicine due to its excellent flexibility， elasticity， high water absorption， biocompatibility， and similarity to biological tissues. Conductive hydrogels also have excellent electrical conductivity compared to traditional hydrogels， which makes them show great potential in emerging fields such as remote health monitoring， human motion detection， electronic skin， human-machine interface and soft robotics. Therefore， in recent years， efforts have been made to develop conductive hydrogels with a variety of properties and explore their applications in various fields. Currently， conductive hydrogels could be classified into electronically conductive hydrogels and ionically conductive hydrogels according to the transmission medium. Usually， conductive hydrogels can be prepared by doping conductive materials into the hydrogel matrix. However， with the continuous deepening of the research on hydrogels， the performance requirements of conductive hydrogels have been increasing， especially the anti-swelling properties of hydrogels. Unwanted swelling in the liquid-phase environment leads to a decrease in the hydrogel’s mechanical properties， electrical conductivity， and is accompanied by a distortion of the sensing signal. Therefore， there is an urgent need to prepare conductive hydrogels with both good electrical conductivity and swelling resistance. In this review， firstly， the preparation methods of different types of conductive hydrogels are discussed. Secondly， several strategies for constructing swelling-resistant conductive hydrogels are discussed， including supramolecular hydrogels， dual-network hydrogels， and so on. Finally， the main application areas of anti-swelling conductive hydrogels are presented.
Highly entangled networks，as a novel design strategy for soft materials，effectively address the contradiction among strength，toughness，and fatigue resistance in traditional crosslinked materials by regulating the topological entanglement structure of molecular chains. This paper systematically reviews five strategies to construct highly entangled networks： high-concentration monomer polymerization，post-crosslinking of highly entangled chains，dual-network synergistic high entanglement of dual networks，macromolecular crosslinking high entanglement，and nanocomposite high entanglement. The molecular design principles，structural characteristics，and performance advantages of each strategy are analysed. In the field of functional applications，this review highlights the innovative applications of highly entangled materials in wear-resistant coatings，durable devices，adhesives，and intelligent actuators，demonstrating the excellent mechanical properties and unique functional characteristics endowed by highly entangled networks. Moreover，the challenges and future directions of highly entangled soft materials are discussed，emphasizing that multi-scale simulation technology，bionic adaptive design，and green manufacturing processes will be important research directions in this field. This review provides systematic theoretical guidance and technical reference for the design and application of functional soft materials with highly entangled networks.
In addressing the inadequate water solubility and bioavailability of baicalin， this study develops a drug carrier that exhibits both antimicrobial and self-healing hydrogel by integrating konjac glucomannan （KGM）-based hydrogel with cyclodextrin encapsulation technology. The successful preparation of baicalin/hydroxypropyl-β-cyclodextrin inclusion complexes is achieved through the utilisation of a saturated solution stirring-freeze-drying method. Subsequent FTIR and XRD analysis demonstrates the effective inclusion of baicalin within the cyclodextrin cavity. The inclusion complexes are loaded into KGM/sodium tetraborate dynamically crosslinked hydrogels， and the resulting hydrogels exhibit excellent swelling properties with a swelling rate of 630.23%. Mechanical tests demonstrate that the hydrogel has significant self-healing capability， with a tensile strength retention rate of 97.80% after healing. In vitro release experiments demonstrate that the system conforms to First-order release model， the cumulative release rate of baicalin reaches 84.33% at 48 h. Antimicrobial experiments confirm that its inhibition rate against Staphylococcus aureus， Escherichia coli and Candida albicans reaches 99.12%， 98.07% and 98.82%， respectively， and the DPPH radical scavenging rate is as high as 93.54%. This study proposes a viable methodology for the development of innovative antimicrobial materials and drug carriers， addressing the challenges of low solubility and poor stability associated with baicalin.
Polyimide aerogel （PIA） possesses excellent thermal stability， remarkable mechanical properties， and good dielectric performance， etc.， and is extensively applied in domains such as aerospace， electronic communication， and adsorption cleaning. Nevertheless， the high shrinkage rate and inferior hydrophobic performance of PIA significantly impact its practical application. Herein， This study meticulously design the molecular structure of polyimide and integrates it with a composite filling process to fabricate a composite aerogel characterized by a low shrinkage rate and superior hydrophobicity. This innovative material is specifically tailored for efficient oil-water separation， aiming to enhance the anti-shrinkage and hydrophobic characteristics of polyimide aerogels （PIA）. ACF/PIA-10 has superior dimensional stability （with the shrinkage up to 12.7%）， high mechanical properties （with the compression strength up to 2.36 MPa），outstanding moisture resistance （with the contact angle up to 111°） and excellent thermal stability （with T 5% up to 519 ℃ in nitrogen）. The addition of activated carbon fibers not only enhances the mechanical properties of the material but also optimizes its pore structure. The composite aerogel exhibits a high adsorption capacity for oils， which makes it have considerable application prospects in the field of adsorption cleaning.
Graphene aerogel，with its advantages of low density，high porosity，and a substantial specific surface area，holds promise for diverse applications in oil absorption. In this study，we employ ethylenediamine chemical grafting and a hydrothermal technique to synthesize graphene aerogel. To further refine its structure，carbon nanotubes （CNTs） are grown within the aerogel matrix using chemical vapor deposition. Subsequently，an octadecylamine surface treatment is applied further to enhance the oil absorption capacity of the material. We conduct a comprehensive investigation of the chemical composition，micromorphology，phase composition，and oil absorption properties of the prepared graphene aerogel material. The results reveal that the formability of the graphene aerogel is significantly influenced by the concentration of graphene oxide and the amount of ethylenediamine. Moreover，following structural optimization and surface modification，the oil absorption capability of the graphene aerogel increases dramatically. The modified three-dimensional graphene aerogel exhibits exceptional oil absorption capacity，with an adsorption capacity of up to 98.2 g·g-1 and an adsorption flux of 9.98×104 L·m-2·h-1. The technological insights obtained from this work will serve as a valuable reference for developing high-performance 3D graphene oil-absorbing materials. The results of this study offer a promising technical foundation for advancements in this field.
As critical equipment capable of replacing firefighters in fire suppression and rescue operations， firefighting robots have garnered increasing attention， with intelligence and autonomy becoming major developmental trends. However， such robots face significant challenges in complex thermal environments during firefield operations， where core control components and sensors for autonomous functionality are at risk of thermal failure. Thus， highly efficient and reliable thermal protection materials and technologies are essential to ensure stable robot performance. This paper focuses on thermal protection for firefighting robots， reviewing key materials including thermal protection coatings， thermal insulating materials， and phase-change energy storage materials， while systematically analyzing research progress in integrated thermal protection strategies and critical component protection design. Current limitations are summarized， particularly the trade-off among high-temperature resistance， lightweight properties， long-term stability issues， and cost constraints. Future research directions are proposed， emphasizing intelligent thermal protection systems， sensor integration with data fusion， and dynamic thermal management， aiming to advance the engineering applications of firefighting robots.
Al2O3-ZrO2-based eutectic ceramics，fabricatedby rapid solidification technology and composed of ultrafine，three-dimensionally intertwined single-crystal domains，represent a distinct category of eutectic oxides. These materials exhibit exceptionally high-temperature mechanical properties，such as strength，toughness，and creep resistance when aligned along the preferred growth direction，rendering them preferred ultrahigh-temperature structural materials for long-term operation in high-temperature oxidizing atmospheres. This paper comprehensively reviews the eutectic systems，advanced preparation techniques，microstructure characteristics，and mechanical properties of Al2O3-ZrO2-based eutectic ceramics，with particular emphasis on their high-temperature mechanical performance. It begins by summarizing the material systems of Al2O3-ZrO2-based eutectic ceramics developed to date，followed by a concise introduction to the basic principles，advantages，limitations，and application areas of their advanced preparation technologies. Finally，a detailed comparative analysis is provided，highlighting the typical microstructures and high-temperature mechanical properties-including creep resistance and flexural strength-of Al2O3-ZrO2-based eutectic ceramics prepared by advanced processes. Compared to traditional eutectic ceramics，Al2O3-ZrO2-based eutectic ceramics fabricatedby rapid solidification technology，characterized by unique microstructures and superior mechanical properties，not only enhance the performance and preparation efficiency of conventional sintered oxide materials but also demonstrate unprecedented potential for applications in extreme environments involving high temperatures，high pressures，and strong oxidation.
Performance metal powder serves as a crucial material in 3D printing additive manufacturing， as the properties of the powder directly influence the microstructure and overall performance of 3D-printed components. The plasma rotating electrode process （PREP） employs high-temperature plasma to melt the end face of a rapidly rotating electrode rod. Subsequently， the molten liquid film is fragmented into droplets， which then solidify into powder under the action of centrifugal force. This paper provides a comprehensive review of the development history， equipment types， powder preparation principles， and performance characteristics of the PREP process. It also delves into the impact of process parameters on the powder's properties and discusses the application of numerical simulation methods in understanding the powder formation mechanism and controlling powder particle size. Furthermore， the paper reviews the progress made in applying PREP-prepared powder materials in the 3D printing manufacturing of aerospace， medical equipment， nuclear power， rail transit， and other equipment sectors. Finally， it is highlighted that the PREP milling process is poised to evolve towards higher purity， finer particle size， narrower particle size distribution， fewer inclusions， higher sphericity， greater efficiency， and lower costs.
To delve into the impacts of multiple brazing thermal cycles at varying peak temperatures on the microstructure and properties of GH4169 alloy， this study conducted a comprehensive examination of how brazing thermal cycle processes influence the precipitates， grain size， tensile properties， and stress-rupture properties of the alloy.The findings reveal that as the thermal cycle temperature rises， the quantity of δ-phase precipitation diminishes， and its morphology undergoes a transformation from needle-like to rod-like and eventually to granular. Within the temperature range of 970-1010 ℃， the grain size experiences minimal alteration. However， when the temperature surpasses 1020 ℃， significant grain growth occurs. Both tensile strength and hardness initially ascend and then descend with an increase in the thermal cycle temperature， reaching their peak values at 1010 ℃. This phenomenon is mainly attributed to the dissolution of an appropriate amount of δ phase and the complete precipitation of γ″ and γ′ strengthening phases at this temperature， while the grain size does not show significant coarsening.The room-temperature impact toughness demonstrates distinct trends across different thermal cycle ranges. In the 970-990 ℃ range， it decreases with rising temperature due to the partial transformation of the δ-phase morphology from needle-like to rod-like. In the 990-1010 ℃ range， it increases with temperature as the δ phase dissolves and the strengthening-phase-free zone vanishes. Nevertheless， a further increase in the thermal cycle temperature leads to a reduction in toughness because of grain growth.The stress-rupture life initially declines and then rises with an increase in the thermal cycle temperature， hitting its lowest point in the 990-1000 ℃ range. This is caused by the partial transformation of the δ-phase morphology from needle-like to rod-like， which promotes microvoid nucleation and reduces the alloy's creep resistance. When the temperature further rises above 1020 ℃， the extensive precipitation of γ″ strengthening phases， along with significant grain growth， substantially enhances the alloy's creep performance. However， the substantial decrease in the needle-like δ-phase content results in increased notch sensitivity.Taking into account both mechanical properties and notch sensitivity， it is recommended to employ brazing thermal cycles around 1010 ℃ to achieve a well-balanced combination of strength and stress-rupture performance. For service environments with higher notch sensitivity requirements， a thermal cycle temperature in the range of 970-980 ℃ can be selected to minimize the risks of creep failure.
To tackle the issue of microstructural segregation in nickel-based alloy weldments and the consequent degradation of joint mechanical properties， this study delves into the impacts of two post-weld heat treatment schedules on the microstructural features and mechanical behavior of gas tungsten arc-welded Incoloy 825 nickel-based alloy joints.The results reveal that both heat treatment procedures lead to a notable coarsening of fine grain boundary carbides in the base metal （BM）. Moreover， the γ′ phase can be precipitated within BM grains through solution treatment combined with two-stage aging. Both post-weld heat treatments facilitate extensive precipitation of the δ and Laves phases in the WZ interdendritic zones， effectively alleviating segregation. Nevertheless， joints subjected to solution treatment and two-stage aging develop microcracks at the interface between the unmixed zone （UMZ） and the heat-affected zone （HAZ）， along with the formation of micropores within the HAZ. Mechanical characterization indicates a substantial increase in microhardness in the weld zone （WZ） after both heat treatment protocols. Solution treatment with single-stage aging maintains hardness levels in the HAZ and BM that are comparable to those in the as-welded state. Joints treated with solution treatment and single-stage aging show a marginal reduction in tensile strength， accompanied by a 9.2% improvement in uniform elongation， and fracture exclusively occurs within the BM. Conversely， the tensile strength of joints treated with solution treatment and two-stage aging significantly rises to 795 MPa， an increase of 17.3%， while the uniform elongation decreases. The fracture localization shifts to the UMZ/HAZ interfacial regions and adjacent HAZ areas， presenting a ductile-brittle mixed fracture morphology.
Aiming at the requirements for specifications and performance of GH3625 alloy seamless tubes used in novel renewable solar tower-type molten salt photothermal power generation absorbers， and addressing the shortcomings of the traditional hot extrusion technology—such as long production cycles， high energy consumption， and difficulties in producing billets with large length-to-diameter ratios—this study adopts the deep drilling method to replace traditional hot extrusion for preparing GH3625 alloy billets. Subsequently， Φ46 mm×4 mm×3000 mm and Φ44.45 mm×1.32 mm×9000 mm GH3625 alloy seamless tubes are manufactured through multi-pass cold rolling and intermediate annealing. EBSD analysis reveals that the grain size of the finished GH3625 alloy seamless tubes prepared by the deep drilling method is comparable to that of tubes produced by traditional hot extrusion technology. Moreover， the alloy microstructure contains a large number of annealing twin boundaries， which refine the grains. In addition， mechanical property test results indicate that the room-temperature and high-temperature properties of the finished GH3625 alloy tubes prepared by the deep drilling method are equivalent to those of tubes made by traditional hot extrusion technology. The room-temperature mechanical properties of both specifications meet the requirements of the ASME SB-444-2021 standard： tensile strength≥690 MPa， yield strength≥276 MPa， and elongation after fracture≥30%.
AA5052 aluminum alloy and 304 stainless steel with the thickness of 3 mm are welded with ZnAl22 flux-cored wire by tungsten inert gas （TIG） fusion-brazed welding. The effect of different welding currents and wire feeding speeds on the macro morphology of butt joints，microstructure of weld seam/steel interface，tensile properties and fracture behavior of the joints is studied. The results show that when the welding current is 110 A and the wire feeding speed is 24 mm/s，the maximum average tensile strength of the butt joints reaches 166 MPa. Fracture primarily occurs at the weld seam/steel interface， exhibiting typical brittle fracture characteristics. The weld seam/steel interface is composed of η-Fe2Al5Zn0.4，η-Zn（Al） and α-Al. With the increase of the welding current，the tensile strength of the joint first increases and then decreases. The white granular δ-FeZn10 appears in the η-Fe2Al5Zn0.4 interfacial layer，and Zn elements are segregated at the η-Fe2Al5Zn0.4/steel interface. The Zn-rich phases at the η-Fe2Al5Zn0.4/steel interface are determined to be Γ-Fe3Zn10 by transmission electron microscopy. It is found that excessively high welding current leads to cracking at the η-Fe2Al5Zn0.4/steel interface. With the increase of wire feeding speeds，the thickness of η-Fe2Al5Zn0.4 decreases gradually，and the phase composition at the weld seam/steel interface remains unchanged. Based on thermodynamic analysis，it is concluded that the formation sequence of intermetallic compounds （IMCs） at the weld seam/steel interface is η-Fe2Al5Zn0.4，δ-FeZn10，Γ-Fe3Zn10.
Three different surface treatments—sandpaper polishing， chemical cleaning， and electrolytic polishing combined with chemical cleaning are employed to conduct hot compression bonding tests on 2024 aluminum alloy. The interface microstructure and the interface healing effect under different surface treatment conditions are investigated using characterization techniques such as OM，SEM， and EBSD. The results reveal that under the three surface treatment conditions， the types of interfacial oxide elements are identical， while variations exist in the quantity and size of the oxides. After holding for 4 h， second-phase particles within the matrix precipitate extensively along grain boundaries and at the bonding interface. For the sandpaper-polished specimen， oxides and second-phase particles at the interface account for approximately 32% of the interface area； this proportion is about 42% for the chemically cleaned specimen， and roughly 28% for the specimen subjected to electrolytic polishing combined with chemical cleaning. Interface healing is achieved through the synergistic action of discontinuous dynamic recrystallization and continuous dynamic recrystallization. Based on the microstructural characteristics of the bonding interface， the interface healing rate is utilized to evaluate the degree of interface healing. After statistical calculations， the order of the interface healing rate is as follows： electrolytic polishing combined with chemical cleaning>sandpaper polishing>chemical cleaning.
Usually，the initial microstructure of hot-rolled and quenched medium-manganese experimental steel is composed of lath martensite matrix and a small amount of tiny granular austenite， also existing apparent Mn-segregation bands. Using double intercritical annealing （holding 60 min at 750 ℃ followed by 60 min at 700 ℃）， austenite reversion transformation in Mn-rich and Mn-lean regions are modulated by stages， which efficiently promoting the refinement of retained austenite grains and the optimization of mechanical stability distribution without apparent variation of volume fraction of retained austenite. The results show that adequate and sustained strain-induced martensite transformation is favored and boosted during uni-axial tensile deformation. Due to synergistic toughening of transformation and twinning induced plasticity effects， excellent combination of strength and ductility， such as the ultra-high total elongation of 85.3% and product of strength and plasticity （PSE） of 73.4 GPa∙% are obtained eventually.
This paper focuses on the problems of uncoordinated microstructure in each layer and difficult control of interfacial microstructure during the hot roll-bonding process of 316L stainless steel and Q370qE carbon steel. The influence of the final rolling temperature on the microstructure and properties of the stainless steel clad plate is investigated. The microstructure of the clad plate is analyzed by metallographic microscope， scanning electron microscope， transmission electron microscope， and energy dispersive spectrometer. The mechanical properties are performed based on the interface tension-shear and tensile tests. The results show that the higher the final rolling temperature， the larger the thickness of the decarburization layer and carburization layer in the interface area of the clad plate， while the diffusion distance of Cr and Ni elements first increases and then decreases. When the final rolling temperature is 840 ℃， the carbon steel layer is composed of proeutectoid ferrite， bainite， and sorbite， and the stainless steel layer is composed of austenite with several fine recrystallized grains. The thickness of the decarburization layer is 40 μm， and the thickness of the carburization layer is 35 μm. With the increase of the final rolling temperature， the interface tension-shear strength of the clad plate first increases and then decreases， while the yield strength and tensile strength both increase， and the increase rate slows down at high temperatures. The tension-shear fracture position of the clad plate is located in the decarburization layer of the carbon steel， and the fracture morphology of tensile shows interface delamination. Therefore， the clad plate final rolled at 840 ℃ achieves the best mechanical performance， with the interface tension-shear strength of 339 MPa， the yield strength of 497 MPa， the tensile strength of 594 MPa， and the elongation after fracture of 18.6%， respectively.
At room temperature， the predominant plastic deformation mechanisms in industrial pure titanium TA2 encompass dislocation slip， twinning， and interfacial interactions. This study combines mechanical analysis performed during roll-forming experiments and utilizes electron backscatter diffraction and optical microscopy to investigate the microscale deformation mechanisms on both the inner and outer surfaces of TA2 sheets during roll forming from 0° to 30°.The research results demonstrate that during the forming process， as the bending angle reaches 20°， a differential stress is exerted on the axis of the hexagonal close-packed structure on the inner and outer sides. On the inner side， the plastic deformation mechanism shifts from the previously dominant pyramidal slip and basal slip to mainly ｛1012｝ tension twinning， which is due to the distinct stress acting on the axis. On the outer side， where the axis is under compressive stress， dislocation slip remains the primary deformation mechanism because the occurrence of ｛1122｝ compression twinning is hindered by its high critical resolved shear stress and the fine-grained nature of the material. As a result， ｛1122｝ compression twinning functions as an auxiliary deformation mechanism on the outer side. These findings offer critical insights into the plastic deformation behavior of TA2 during the roll-forming process.
The ship's anchor chain rings， sliding bearings， and other components exposed to seawater are subjected to long-term corrosion and wear， collectively referred to as tribocorrosion. The tricoborrosion resistance of these materials directly affects the operational safety of marine equipment. In this study， the in-situ electrochemical testing method for corrosion and wear are employed to investigate the tribocorrosion resistance of six commonly used materials in artificial seawater environments： anchor chain steel （CM690）， bearing steel （GCr15）， high-strength marine steel （AH36 steel）， cast iron for diesel engine cylinder liners （HT350）， tin bronze for plain bearing bushings （QSn8）， and steel most commonly used in mechanical structures （45 steel）. The objective is to analyze their corrosion resistance and damage resistance mechanisms. The results show that under pure corrosion conditions， QSn8 exhibits a significantly higher self-corrosion potential compared to other iron-carbon alloys， and has the lowest corrosion rate （0.09 mm/a）. However， under corrosion wear conditions， HT350 demonstrates a relatively low wear loss rate （6.28×10-6 mm³/（N·m））， second only to QSn8 （3.47×10-6 mm³/（N·m））. This is attributed to its high hardness and the lubricating effect of graphite flakes within the cast iron matrix. The other four materials exhibits higher wear rates，around （1.22-1.88）×10-5 mm³/（N·m）. QSn8 shows excellent resistance to both corrosion and wear in simulated seawater conditions， making it a promising candidate for tribocorrosion-resistant components. However， its relatively high cost may limit its widespread application. If other mechanical performance requirements are met， HT350 can serve as a cost-effective alternative.
The characteristics of palladium layer on the surface of copper wire are important factors affecting the quality of free air ball （FAB） and bonding during chip packaging. In this paper， palladium-coated copper wires with different coating speeds and coating temperatures are prepared by halogen-free direct coating process. The effects of coating speed on the morphology of the coating and the characteristics of FAB are studied. The results show that with the increase of coating speed， the coating time decreases， and the uniformity of the distribution of palladium particles on the surface of the copper wire becomes worse. The agglomeration of palladium particles with uneven local distribution causes the concentration of palladium particles to be too high， and the agglomeration area of palladium particles on the surface of the coating increases. Under the plating speed of 50 m/min， the distribution of palladium on the surface of the coating is more uniform. With the increase of coating speed， the diameter of FAB decreases gradually. The difference of palladium content between the agglomeration area and the non-agglomeration area of Pd particles on the surface of Pd-coated copper wire increases， and the consistency of FAB sphere size gradually decreases. At a lower coating speed of 50 m/min， the distribution of palladium content on the surface of FAB is relatively uniform. At a higher coating speed of 100 m/min， a large number of agglomerated palladium particles on the surface of the coating are remelted to form a large area of continuous palladium-rich area on the surface of the FAB， and the uniformity of palladium redistribution is poor. Considering the uniformity of FAB size and surface palladium redistribution， the coating speed of 50 m/min and the coating temperature of 400 ℃ are the better process parameters for the coating of palladium-coated copper wire.
The C-SiC composite coating is integrally prepared on the surface of a single-crystal Si（100） substrate using chemical vapor deposition（CVD） with graphite as the extra-C source and HMDSO-H2 as the precursor system. The surface morphology， phase composition， mechanical properties， and thermal shock resistance of the composite coatings are analyzed by scanning electron microscopy（SEM）， X-ray diffraction（XRD）， nanoindentation and scratch testing. The results show that the extra-C source enable simultaneous deposition of a carbon buffer layer and SiC coating. The prepared C-SiC composite coating exhibits a total thickness of 50 μm （including a 10 μm-thick C buffer layer）， dense structure， and excellent adhesion to the single-crystal Si substrate. The coating shows outstanding thermal shock resistance， with surface cracks emerging after 20 thermal cycles between 20 ℃ and 1200 ℃， but no warping or delamination occurs. The nanoindentation reveals that hardness and elastic modulus of the composite coating are 23.25 GPa and 272.3 GPa， respectively， while the scratch testing indicates an interfacial adhesion strength between the coating and substrate is 29 N.
The Cr coatings are fabricated on 304 stainless steel substrates using cold spray and electroplating methods. The particle deposition behavior and coating formation mechanism of Cr are clarified by analyzing the surface morphology， cross-sectional microstructure， and nanomechanical properties of the cold-sprayed Cr coatings. The results show that the electroplated Cr coating contains numerous vertical cracks， while the cold-sprayed Cr coating exhibits an irregular but compact and defect-free interface with the substrate. In addition， the surface of the cold-sprayed coating presents a large number of craters， and the near-surface region consists of fine equiaxed grains. The nanohardness in the region increases by 41.37%-62.17% compared with that of undeformed Cr particles， indicating that subsequent particles produce work hardening due to shot-peening effects upon impacting the pre-deposited coating. The hardening hinders cooperative plastic deformation between incoming particles and the existing coating， thereby reducing the feasibility of further deposition. Based on the surface morphology and the gradient distribution of nanohardness， the deposition mechanism for Cr coatings on 304 stainless steel is proposed， involving the disruption of the substrate’s oxide film， the formation of the initial coating layer， and the surface morphological evolution induced by shot-peening strengthening.
In this study，B4C-C green containing carbon fibers are prepared by hot pressure molding process used carbon fiber，boron carbide powder，and graphite powder as raw materials，phenolic resin as molding agent，wherein，carbon fiber and powder are dispersed through shear mixing. Then B4C composites （RBBC） are prepared by reaction sintering of B4C-C green at 1550 ℃. The influence of carbon fiber content on the density，composition，structure，and mechanical properties of composites is studied.The results show that the RBBC has the best synthetic property when the volume fraction of carbon fiber reaches 5% in the green.The bending strength，fracture toughness，elastic modulus，and hardness reach 453 MPa，6.7 MPa·m1/2，349 GPa，and 23.5 GPa，respectively. Carbon fiber partially reacts with silicon as a "slow-release" carbon source during the reaction sintering process，slowing down the reaction rate，avoiding material cracking and deformation during the reaction sintering process. It is also helpful for reducing the size of Si islands and content of residual Si in composites，refining the SiC grains generated by the reaction.
The baseline seal structure is widely used in the thermal protection of aircraft due to its excellent thermal insulation and stability. However， prolonged exposure to high temperatures and heavy loads in service can easily lead to permanent deformation of the seal， limiting its reusability. In this study， elastic elements woven from GH4169 alloy wires are used to fabricate ceramic fiber baseline seals with different internal filling structures， such as loose fiberfill， unidirectional fiber tow， and braided fiber bundles. The effects of the cotton core filling structure， compression cycles， and heat treatment of the elastic elements on the elastic property of the seals are investigated. The results show that as the compression level increases， the recovery ratios of the seals with the three filling structures decrease to varying degrees. When the compression level reaches 30%， the seal with the loose fiberfill structure exhibits the highest recovery ratio of 95.93%. As the number of compression cycles increases， the recovery ratio of the seal decreases. After standard heat treatment of the elastic elements， the peak load of the elastic elements at a 60% compression level decreases from 451.25 N/m （untreated） to 196.25 N/m， while the recovery ratio of the seals increases from 77.87% to 87.78%. Theoretical calculations and experimental analysis of the seal’s tightness reveal that as the pressure difference increases， the leak rate of the seal rises. The experimental values of the leak rate are higher than the theoretical values， and the tightness of the seal is influenced by its elastic property and the insulating cotton core.
3D microelectronic packaging imposes extremely stringent requirements on the size and precision of Cu core balls. To obtain Cu core balls that meet these requirements， it is essential to ensure the stability during the droplet jetting process and to precisely control the droplet size as needed. This study employs the pulsated orifice ejection method to prepare monodisperse Cu particles. The key parameters affecting particle size are determined based on the Hagen-Poiseuille law， and the relationship between these key parameters and the stability and size of Cu droplet jetting is investigated in detail. The influence of temperature and differential pressure determines whether droplets can be jetted， while the pulse waveform and the rod distance primarily control the particle size. Orthogonal experiments reveal that the particle size is co-influenced by multiple parameters， among which the voltage of the pulse waveform has the most significant impact， and the the particle size increases with the increase of the voltage. Adjusting the rod distance can regulate the stability of the jetting process. Through the analysis of the jetting window and orthogonal experiments， appropriate key parameters are selected to prepare Cu particles with target sizes of 100 μm and 200 μm. The actual obtained particle sizes are 96.27 μm and 200.69 μm， with standard deviations of approximately 2.67 μm and 2.64 μm， respectively， and sphericity values both exceeding 0.95. The prepared Cu particles exhibit uniform size and high sphericity， meeting the requirements for Cu core balls.
The construction of abundant active sites and enhancement of pollutant-specific selectivity on heterogeneous catalyst surfaces are crucial for efficient pollutant removal via persulfate-based advanced oxidation processes. The incorporation of carbon dots （CDs） into copper-based oxides to construct multivalent metal species can significantly improve the activation capability of peroxydisulfate （PS）. In this study，a simple calcination method is employed to regulate the valence state of Cu in copper-based oxides using CDs，resulting in the synthesis of a CDs/CuO x composite with multiphase structures containing Cu0，Cu2O，and CuO. In the degradation of tetracycline （TC） （used as a model pollutant），the CDs/CuO x composite excellent activation capability. Under the reaction conditions of TC concentration （50 mg/L），PS concentration （0.5 mmol/L），and catalyst concentration （0.06 g/L），the degradation efficiency of TC reaches 99% within 60 min，with an apparent reaction rate constant of 0.066 min-1. This reaction rate is 6.6 times that of CuO. Cu⁰ acts as a continuous electron donor，not only induces the generation of selective singlet oxygen （¹O₂） but，more importantly，promotes the Cu2+/Cu+ cycle reaction. This cycle generates hydroxyl radicals （·OH） and improves activation efficiency. The use of CDs regulates the coexistence of multivalent Cu active sites in the catalyst，which enhances the activation capability for PS，providing a new idea for the efficient design of catalysts.
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