Traditional Powder Research Articles

Effect of binder content and sintering time on the microstructure and mechanical properties of gradient cemented carbides with Ni binder

Replacement of Co by alternative Ni binder in gradient cemented carbide is an effective way to reduce the health concerns associated with Co powders. In the present work, gradient cemented carbides with different Ni contents and gradient sintering times were prepared by traditional powder metallurgy with a two-step sintering method. The microstructure of cemented carbide including the gradient layer formation was analyzed by XRD, SEM, EDS, TEM, and EBSD. The thickness of the gradient layer is almost proportional to the square root of sintering time, indicating that the gradient layer formation is a diffusion-controlled process. The atomic migration can be accelerated to form a thicker gradient layer with the increase of the binder content. The coherent interface of the Ti(C, N) core-rim structure for the gradient cemented carbides with Ni binder was revealed. With the increase in binder content, the average grain size of the WC phase is increased. The hardness and fracture toughness of the cemented carbides were also studied and analyzed according to the crack propagation behavior and the distribution of dislocation and stress indicated by KAM and GND. The variation of the hardness and the fracture toughness with the sintering time is mainly related to the density and the grain size of hard phases, while the change of the mechanical properties along with the Ni content probably results from the local dislocation density and the stress in the cemented carbides. The cemented carbide can obtain a good combination of hardness and fracture toughness with 10 wt% Ni gradient sintered for 2h.

Leaf-like networks consisting of TiO2/biochar composite for enhanced adsorptive-photocatalytic treatment of antibiotic and dye

The problematic solid-liquid separation and low light utilization of traditional powder composites have hindered the industrial application prospect of adsorptive-photocatalytic technology. In this work, a Sycamore leaf-like hierarchically porous structured TiO2/biochar composite (LBT) was synthesized via a sol-hydrothermal method. The distinctive leaf structure effectively addressed the issue of transparency while simultaneously facilitating recyclability. LBT exhibited a high removal efficiency of 95.65 % for MO under simulated sunlight, with a maximum adsorption capacity of 284.06 mg/g. The synergistic action of adsorption-photocatalysis resulted in the degradation of 74.17 % adhered MO on LBT, enabling the recyclability and reusability of the composite material. Furthermore, employing LBT achieved removal efficiency of 80.78 % and degradation of 50.21 % for CIP, respectively. This work provides a practical approach for the efficient removal of organic pollutants from water by utilizing multifunctional materials with adsorptive-photocatalytic properties.

Optimizing Silver Paste Conductivity with Controlled Convection for Nanowrinkle Growth.

Conductive silver paste plays a crucial role as an interconnecting material between electrodes and circuits in electronic circuits and solar cells. The quality of the silver paste is greatly influenced by the preparation of the conductive-phase silver powder and the sintering process. This study investigated the impact of fluid dynamics on the preparation of silver powder. Combined with X-ray diffractometer characterization and molecular dynamics simulation, the formation mechanism of wrinkled silver powder was explained. The wrinkled silver powder replaced the traditional smooth spherical silver powder, and the point contact between the smooth silver powder turned into a line and surface contact. After mixing and sintering with the micrometer flake silver powder, the electrical conductivity and sintering morphology of the silver paste were improved. Compared with the silver content of conventional silver paste (≥75 wt %), the silver paste of (9.23 ± 0.68) × 10-6 Ω cm can be prepared by curing at 250 °C for 45 min when wrinkled powder/flake powder = 1:1 and silver paste content was only 66.7%. This research work provides a new idea for the morphology control of submicrometer silver powder, which has important applications in the field of low-temperature silver paste for new N-type batteries.

Investigation of the Bonding Mechanism of Al Powder Particles through Pulse Current Sintering Technology

Compared with traditional powder metallurgy, pulse current sintering is an advanced powder-forming technology, but its bonding mechanism is still an open topic for debate. In this paper, pulse current sintering is used as the connection technology and millimeter-sized Al particles are used as the research object. In the whole sintering process, no pressure was loaded; the function of the pulse current was the only source of heat with which to achieve the bonding of Al particles. The bonding mechanism of pulse current sintering was investigated from the perspective of material connection behavior. The results show that the pulse current density of the particle surface reaches 3.48 × 105 A/m2 instantly, while the current density of the particle center is only 8187 A/m2 at the initial stage, which is the main difference between pulse current sintering and traditional powder metallurgy sintering. With the densification process, the current density and temperature distribution in the contact region as well as the center of Al particles contact region tend to be more consistent. Finally, dense interfacial bonding was obtained, and the contact region of Al particles also demonstrated a high hardness value of 0.6385 GPa and yield strength value of 212.83 MPa. The whole process can be considered as a comprehensive action of melting (evaporation), diffusion, and plastic deformation. Based on the above results, a new technology, named high-frequency pulse current sintering, was proposed.

Microstructure, compressive performance and wear resistance of pure molybdenum additively manufactured via laser powder bed fusion

Pure molybdenum (Mo) additively manufactured via laser powder bed fusion is challenging due to its high laser reflectivity and sensitivity to cracking. To achieve crack-free pure Mo alloy and enhance production efficiency, this study employs a high-power (350 W) printing process with a layer thickness of 30 μm, resulting in the successful fabrication of pure Mo with a relative density of 99.2%. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) revealed that the pure Mo specimens prepared by LPBF process exhibited different preferential grain orientations and lattice distortions in various building directions, with higher texture strength on the XOZ plane and greater lattice distortion on the XOY plane. The hardness of the pure Mo specimens reached 208 HV, with uniaxial compressive strength and elongation at 535 MPa and 20.9%, respectively, surpassing existing literature values by 37.2% and 8.0%. Furthermore, the dry friction behavior and mechanism of LPBF-manufactured pure molybdenum were investigated for the first time and compared to traditional powder metallurgy. Consequently, this research offers valuable insights for manufacturing crack-free LPBF pure molybdenum components with 30 μm layer thickness, boasting superior mechanical and wear resistance.

A stretchable gel-type floating material boosts photo-Fenton-adsorption for efficient purification of mineral processing wastewater

Organic floatation reagents and heavy metals are the main pollutants produced from mineral processing industries. Traditional powder material is facing the challenges of difficult solid–liquid separation and fast dissolution during the wastewater treatment. In this paper, a stretchable halloysite based gel-type floating material (GF-HNTs@Mo/Fe) was synthesized to trigger photo-Fenton and adsorption reaction for the purification of the beneficiation wastewater. GF-HNTs@Mo/Fe exhibits good hydrophilicity which is very beneficial to suspend in water to absorb sun light and contact with pollutants under the force of hydrogen bond. Compared to single HNTs@MoS2/FeOOH powder material, GF-HNTs@Mo/Fe can be fabricated to any size and reserve most performance. Under optimized conditions, GF-HNTs@Mo/Fe can continuously remove aniline aerofloat (AAF), Cd2+ and COD both from simulated wastewater and actual lead zinc copper ore beneficiation wastewater over ultra-long time of 288 h, and still remain over 50 % treatment ability. Especially, after 13d treatment of actual beneficiation wastewater, 97.12 % of Cd2+, 85.46 % of AAF, 53.28 % of COD and 46.67 % of TOC still could be eliminated by GF-HNTs@Mo/Fe. Owing to the robust mechanical strength of GF-HNTs@Mo/Fe, it can be easily recovered for reuse and avoid secondary pollution. This GF-HNTs@Mo/Fe floating photo-Fenton-adsorption system not only solves solid–liquid separation issue in powder system, but decreases the drawback of performance loss when powder material was fabricated to bulk material.

A Review on Traditional Processes and Laser Powder Bed Fusion of Aluminum Alloy Microstructures, Mechanical Properties, Costs, and Applications.

Due to its lightweight, high strength, good machinability, and low cost, aluminum alloy has been widely used in fields such as aerospace, automotive, electronics, and construction. Traditional manufacturing processes for aluminum alloys often suffer from low material utilization, complex procedures, and long manufacturing cycles. Therefore, more and more scholars are turning their attention to the laser powder bed fusion (LPBF) process for aluminum alloys, which has the advantages of high material utilization, good formability for complex structures, and short manufacturing cycles. However, the widespread promotion and application of LPBF aluminum alloys still face challenges. The excellent printable ability, favorable mechanical performance, and low manufacturing cost are the main factors affecting the applicability of the LPBF process for aluminum alloys. This paper reviews the research status of traditional aluminum alloy processing and LPBF aluminum alloy and makes a comparison from various aspects such as microstructures, mechanical properties, application scenarios, and manufacturing costs. At present, the LPBF manufacturing cost for aluminum alloys is 2-120 times higher than that of traditional manufacturing methods, with the discrepancy depending on the complexity of the part. Therefore, it is necessary to promote the further development and application of aluminum alloy 3D printing technology from three aspects: the development of aluminum matrix composite materials reinforced with nanoceramic particles, the development of micro-alloyed aluminum alloy powders specially designed for LPBF, and the development of new technologies and equipment to reduce the manufacturing cost of LPBF aluminum alloy.

Synthesis and characterization of W-Y2O3 composites with core-shell structure via wet chemical method in an acidic solution

W-Y2O3 materials are the ideal PFMs in fusion reactors because of their excellent performance, however, due to the limitation of traditional powder preparation methods, W-Y2O3 materials face the challenges of coarse particles, high brittleness and low strength, and cannot meet the applications. The synthesis of high-quality powder is the first and crucial step in preparing high-performance tungsten based materials. Therefore, in this manuscript, W-Y2O3 powders with a nano and core-shell structure were synthesized by wet-chemical method in an acidic solution, and then the fine-grained W-Y2O3 composites was fabricated by spark plasma sintering (SPS) under 1873 K. The performance of W-Y2O3 composites and powders were analyzed by XRD, SEM and TEM. In particular, the existence form, distribution characteristics, evolution behavior of the second phase of Y2O3 and the interface characteristics of W/Y2O3 in powders and bulks were systematically discussed. H+ makes the self-assembly be inhibited in sol and produces the holes on surface of precursor powder during the reduction reaction. This structure of the precursor powder creates lots of paths which allow H2 to react with deep particles, resulting in ultrafine particle size, a core-shell structure and uniform element distribution. The powder of W-Y2O3 show obvious core-shell structure, and the thickness of the shell structure is uneven, about 7.7–15.2 nm, while the average grain size of these powders is 62.7 nm. Meanwhile, the W-Y2O3 alloys prepared from these powders show refinement and uniformity, the average grain size is 700 nm. Moreover, the new phase of Y2WO6 was observed at the W/Y2O3 interface, which has a semi-coherent relationship with Y2O3 and W, respectively. This is very conducive to improving the W/Y2O3 interface and thus significantly improving the performance. These results indicate that wet-chemical method in an acidic solution is a promising way to approach for synthesizing nano W-Y2O3 powders with core-shell structure and improve W/Y2O3 interface performance.

Coagulating blood into adhesive gel by hybrid powder based on oppositely charged polysaccharide/tannic acid-modified mesoporous bioactive glass

Hemostatic powder is widely utilized in emergency situations to control bleeding due to its ability to work well on wounds with irregular shapes, ease of application, and long-term stability. However, traditional powder often suffers from limited tissue adhesion and insufficient support for blood clot formation, leaving it susceptible to displacement by the flow of blood. This study introduces a hemostatic powder composed of tannic modified mesoporous bioactive glass (TMBG), cationic quaternized chitosan (QCS), and anionic hyaluronic acid modified with catechol group (HADA). The resulting TMBG/QCS/HADA based hemostatic powder (TMQH) rapidly absorbs plasma, concentrating blood coagulation factors. Simultaneously, the water-soluble QCS and HADA interact to form a 3D network structure, which can be strengthened by crosslinking with TMBG. This network effectively captures clustered blood coagulation factors, leading to a strong and adhesive thrombus that resists disruption from blood flow. TMQH exhibits superior efficacy in promoting hemostasis compared to Celox™ both in rat arterial injuries and non-compressible liver puncture wounds. TMQH demonstrates excellent antibacterial activity, cytocompatibility, and blood compatibility. These outstanding superiorities in blood clotting capability, wet tissue adhesion, antibacterial activity, safety for living organisms, ease of application, and long-term stability, make TMQH highly suitable for emergency hemostasis.

Lab-on-Device Synthesis of Hierarchical Macro/Mesoporous WO3 Semiconducting Films for High-Performance H2S Sensing.

The performance consistency of the gas sensor is strongly dependent on the interface binding between the sensitive materials and the electrodes. Traditional powder coating methods can inevitably lead to differences in terms of substrate-film interface interaction and device performance, affecting the stability and lifetime. Thus, efficient growth of sensitive materials on device substrates is crucial and essential to enhance the sensing performance, especially for stability. Herein, hierarchically ordered macro/mesoporous WO3 films are in situ synthesized on the electrode via a facile soft/hard dual-template strategy. Orderly arrayed uniform polystyrene (PS) microspheres with tailored size (ca. 1.2µm) are used as a hard template, and surfactant Pluronic F127 as a soft template can co-assemble with tungsten precursor into ordered mesostructure in the interstitials of PS colloidal crystal induced by solvent evaporation. Benefiting from its rich porosity and high stability, the macro/mesoporous WO3-based sensor shows high sensitivity (Rair/Rgas = 307), fast response/recovery speed (5/9 s), and excellent selectivity (SH2S/Smax > 7) toward 50ppm H2S gas (a biomarker for halitosis). Significantly, the sensors exhibit an extended service life with a negligible change in sensing performance within 60 days. This lab-on-device synthesis provides a platform method for constructing stable nanodevices with good consistency and high stability, which are highly desired for developing high-performance sensors.

Resolving the long-standing discrepancy in Fe3Al ordering mobilities: A synergistic experimental and phase-field study

This study addressed the long-standing challenge of determining the growth kinetic of Antiphase Domains (APDs) with D03-ordered structure in Fe3Al by the combination of phase-field (PF) simulations and transmission electron microscopy (TEM) observation. The “shape coefficient” which correlates the growth rate of APD with 3-dimensional intricate shape and the shrinking rate of 2-dimensional circular antiphase boundaries (APBs) in thin film was assessed through a comparative analysis of PF simulations involving the shrinking of 2D circular APBs and the growth of 3D APDs emerged from a disordered state. Simultaneously, the increase rate in APD size in bulk samples after heat treatment was measured using TEM. By incorporating the calculated shape coefficient and experimental data on APD growth rates, we successfully derived accurate values of mobility for forming D03 type ordered structure. The ordering mobilities evaluated by this approach align more closely with those obtained through traditional X-ray powder diffraction of order-order relaxation rather than those obtained through in-situ TEM observation. This finding lays the foundation for optimizing heat treatment conditions to regulate APD structure and enhance the superelasticity of Fe3Al primarily due to the interaction between dislocation and APBs. This methodology can be extended to estimate the ordering mobility of other intermetallic.

Facile synthesis of PA photocatalytic membrane based on C-PANI@BiOBr heterostructures with enhanced photocatalytic removal of 17β-estradiol

The prevalence of 17β-estradiol (E2) in wastewater has attracted widespread attention due to the negative impacts on ecological environments and human health. Nowadays, photocatalysis has been emerged as an efficient technology for E2 containing wastewater treatment. However, traditional powder photocatalysts face challenges such as easy agglomeration, secondary pollution and difficult recovery, limiting their large-scale application. In this study, a photocatalytic PA/C-PANI@BiOBr membrane was fabricated by immobilizing polyaniline (PANI) layer and BiOBr nanosheets on polyamide (PA) membrane through in-situ chemical bath deposition. This process leveraged the strong hydrogen bond interaction between PANI and PA, with the fine PANI fibers providing nucleation sites for the in-situ growth of BiOBr nanosheets. By repeating the immersion process, we controlled variations in the coverage density and morphology of BiOBr on the membrane surface. The PA/C-PANI@BiOBr membrane exhibited outstanding light absorption and photocatalytic performance. Notably, the optimal PA/C-PANI@BiOBr-10 membrane achieved 100 % removal efficiency of 3 mg L−1 E2 within 40 min. In dynamic cyclic experiments, PA/C-PANI@BiOBr-10 membrane maintained stable permeability and high removal efficiency of pollutants. The photocatalytic mechanism underlying these results was elucidated through photoelectric testing and further photocatalytic experiments. Furthermore, the PA/C-PANI/BiOBr-10 membrane demonstrated remarkable durability over multiple consecutive cycles, with E2 removal efficiency remaining above 96.5 % after 5 cycles.

Swift Covalent Gelation Coupled with Robust Wet Adhesive Powder: A Novel Approach for Acute Massive Hemorrhage Control in Dynamic and High-Pressure Wound Environments.

The quest for efficient hemostatic agents in emergency medicine is critical, particularly for managing massive hemorrhages in dynamic and high-pressure wound environments. Traditional self-gelling powders, while beneficial due to their ease of application and rapid action, fall short in such challenging conditions. To bridge this gap, the research introduces a novel self-gelling powder that combines ultrafast covalent gelation and robust wet adhesion, presenting a significant advancement in acute hemorrhage control. This ternary system comprises ε-polylysine (ε-PLL) and 4-arm polyethylene glycol succinyl succinate (4-arm-PEG-NHS) forming the hydrogel framework. Na2HPO4 functions as the "H+ sucker" to expedite the amidation reaction, slashing gelation time to under 10 s, crucial for immediate blood loss restriction. Moreover, PEG chains' hydrophilicity facilitates efficient absorption of interfacial blood, increasing the generated hydrogel's cross-linking density and strengthens its tissue bonding, thereby resulting in excellent mechanical and wet adhesion properties. In vitro experiments reveal the optimized formulation's exceptional tissue compliance, procoagulant activity, biocompatibility and antibacterial efficacy. In porcine models of heart injuries and arterial punctures, it outperforms commercial hemostatic agent Celox, confirming its rapid and effective hemostasis. Conclusively, this study presents a transformative approach to hemostasis, offering a reliable and potent solution for the emergency management of massive hemorrhage.

Grain size prediction for stainless steel fabricated by material extrusion additive manufacturing

Most traditional powder melting-based additive manufacturing (AM) technologies generally yield high-performance parts at the expense of additional cost and energy consumption. As an economical and efficient alternative method, material extrusion (ME) that deploys polymer-based filaments with highly filled metal particles offers the possibility of scalable, low-cost fabrication of metal components. As a critical step, sintering governs the mechanical strength and geometry of the final parts. The grain growth behavior induced during sintering should be well controlled to achieve the parts with the desired mechanical performance. Due to the nature of AM, grain growth kinetics could also involve extremely complex grain boundary migration and atomic diffusion mechanisms caused by the heterogeneous pore distribution. In this work, an analytical model was developed to predict and understand the grain growth behavior of stainless steel (SS) 316L built by ME-based sintering-assisted AM. Such a model accounts for anisotropic viscosity parameters calibrated through a three-dimensional dilatometry test, enabling the prediction of grain size evolution during sintering. Grain growth kinetic parameters were further identified by the grain size data at the heating and holding stages. To validate and generalize the model, we also conducted the grain size evolution prediction under different sintering temperature profiles for as-built SS 316L specimens. This work will provide scientific insights into the grain growth behavior of metal parts built by this AM technique and its understanding can be readily transferred to other sintering-assisted AM processes like binder jetting and ink writing for metal structure creation.

A Comprehensive Review of Fingerprint Development : Exploring Unconventional Powder-Based Techniques

Fingerprint development remains a crucial aspect of forensic science, aiding in the identification and resolution of criminal cases. This review paper systematically explores the efficacy and potential of various unconventional and natural substances in fingerprint development. Focusing on an array of substances such as turmeric powder, Fuller's clay powder (Multani Mitti), food color, Holi color, durian seeds powder, soil powder, talcum powder, traditional powders, pooja materials, corn seed powder, silica gel G, broccoli powder, medicine powder, salt, sugar powder, and brick powder, this paper discusses their applicability, advantages, limitations, and comparative effectiveness in developing latent fingerprints. The review encompasses studies and experiments conducted to assess the suitability of these substances for fingerprint development across different surfaces and environmental conditions. Additionally, this article examines the environmental and cost-effective benefits of using natural and non-conventional materials in forensic investigations and their sustainability and availability compared to traditional chemical reagents.

Recyclable and dual-functional Ag3PO4/3D graphene aerogel photocatalysts for simultaneous water oxidation and pollutant degradation

Exploiting recyclable and reusable photocatalysts in pollutants elimination and water splitting has drawn extensive research attention for solving the increasing energy and environmental issues. Herein, we designed a high-performance dual functional Ag3PO4/three-dimensional (3D) graphene aerogel (APGA) photocatalyst, in which the 3D GA with extremely lightweight and high mechanical stability served as the support for Ag3PO4 particles, preventing the serious weight loss during the recovery process. Moreover, different from the traditional powder photocatalysts, the application of 3D GA support avoided the secondary contamination caused by the catalyst residue during the reaction. The abundant hydroxyl groups on the surface of porous 3D GA prevented the aggregation of Ag3PO4 particles, forming a close interfacial contact. Profiting from the large number of active sites and high conductivity of 3D GA, the optimized APGA-12 sample showed excellent O2 generation (814.1 μmol·g−1) and synchronous Cr (VI) reduction (87.5 %) efficiency. In addition, the APGA-12 sample also exhibited excellent carbamazepine (CBZ) degradation activity (99 % within 30 min) in the presence of peroxymonosulfate (PMS). Cycling experiments combined with the scaled-up reactions verified the good mechanical and chemical stability of APGA samples. This work provided a promising strategy for solving the problems of catalyst recycling in the field of pollutant degradation and water oxidation.

An Evaluation of the Impact of 60Co Irradiation on Volatile Organic Compounds of Olibanum Using Gas Chromatography Ion Mobility Spectrometry.

Olibanum is a resinous traditional Chinese medicine that is directly used as a powder. It is widely used in China and is often combined with other traditional Chinese medicine powders to promote blood circulation and relieve pain, as well as to treat rheumatism, rheumatoid arthritis, and osteoarthritis. Powdered traditional Chinese medicine is often easily contaminated by microorganisms and 60Co irradiation is one of the good sterilization methods. Volatile organic compounds (VOCs) are the main active ingredient of olibanum. The aim of this study was to validate the optimum doses of 60Co irradiation and its effect on VOCs. 60Co irradiation was applied in different doses of 0 kGy, 1.5 kGy, 3.0 kGy, and 6.0 kGy. Changes in VOCs were detected using gas chromatography ion mobility spectrometry. A total of 81 VOCs were identified. The odor fingerprint results showed that, with an increase in irradiation dose, most of the VOCs of olibanum changed. Through principal component analysis, cluster analysis, and partial least squares discriminant analysis, it was demonstrated that, at 1.5 kGy, the impact of radiation on the VOCs of olibanum was minimal, indicating this is a relatively good irradiation dose. This study provides a theoretical basis for the irradiation processing and quality control of resinous medicinal materials such as olibanum and it also provides a good reference for irradiation technology development and its application to functional foods, thus making it both significant from a research perspective and useful from an application perspective.

Efficient and environmentally friendly white light-emitting diodes with InP-based quantum dots embedded in mesoporous silica

As one of the promising next-generation light conversion materials, indium phosphide quantum dots (InP QDs) deserve much attention due to their great optical performances and environmentally friendly properties in particular. Herein, InP-based QDs are embedded into mesoporous SBA-15 and solid QDs/SBA-15 composites are prepared, which exhibit 1.5 times higher photoluminescence quantum yield (PLQY) and narrower full width of half maximum (FWHM) than traditional QDs powder thanks to the reduction of light reabsorption and the optical waveguide effect of mesoporous structure. These advantages contribute to the performance enhancement of light-emitting diodes (LEDs). The luminous efficacy of the LED with green QDs/SBA-15 is 99.49 lm/W, which is higher than that of QDs powder (66.14 lm/W). In addition, the white LED fabricated with green and red InP-based QDs/SBA-15 shows luminous efficacy of 61.38 lm/W. More importantly, the luminous efficacy of the white LED is improved to 129.62 lm/W when using the K2SiF6:Mn4+ instead of red InP-based QDs/SBA-15, because the K2SiF6:Mn4+ does not absorb the emission from green InP-based QDs/SBA-15. This value is higher than those white LEDs with InP-based QDs reported previously. It is believed that this study demonstrates the promising potential of InP-based QDs for optoelectronic applications.

Nano FeCoNi-based high-entropy alloy for microwave absorbing with high magnetic loss and corrosion resistance

With the development of modern communication and military technology, the protection of electromagnetic wave pollution and radar stealth technology have been widely concerned. In this background, the magnetic metals were widely used due to the strong ferromagnetism, which can induce strong magnetic loss to the electromagnetic wave. However, it remains challenging to precisely control the wave-absorbing performance of individual magnetic metals, and there are issues with poor corrosion resistance and high temperature resistance. Therefore, the alloy powders based on Fe, Co, and Ni in this work were prepared by wet chemical method at room temperature. Different from most of the traditional powder metallurgy methods, the wet chemical method enables us to obtain binary, ternary and quaternary alloys with a nanometer-scale and uniform distribution, all products have a microscopic morphology of 300–500 nm spheres. The FeCoNi alloy powder shows an effective absorption band (RL<-10 dB) of 7 GHz in the high frequency electromagnetic wave range at an ultrathin thickness of 1.5 mm, which has a high temperature magnetism (Tc >900 K) and excellent corrosion resistance. Further doping of Cu to form a quaternary alloy can improve the corrosion resistance and maintain the original wave-absorbing properties, while doping of Mo and Sn can adjust the position of the effective absorption bandwidth.

Gluing blood into adhesive gel by oppositely charged polysaccharide dry powder inspired by fibrin fibers coagulation mediator

Hemostatic powders that adapt to irregularly shaped wounds, allowing for easy application and stable storage, have gained popularity for first-aid hemorrhage control. However, traditional powders often provide weak thrombus support and exhibit limited tissue adhesion, making them susceptible to dislodgment by the bloodstream. Inspired by fibrin fibers coagulation mediator, we have developed a bi-component hemostatic powder composed of positively charged quaternized chitosan (QCS) and negatively charged catechol-modified alginate (Cat-SA). Upon application to the wound, the bi-component powders (QCS/Cat-SA) rapidly absorb plasma and dissolve into chains. These chains interact with each other to form a network, which can effectively bind and entraps clustered red blood cells and platelets, ultimately leading to the creation of a durable and robust thrombus. Significantly, these interconnected polymers adhere to the injury site, offering protection against thrombus disruption caused by the bloodstream. Benefiting from these synthetic properties, QCS/Cat-SA demonstrates superior hemostatic performance compared to commercial hemostatic powders like Celox™ in both arterial injuries and non-compressible liver puncture wounds. Importantly, QCS/Cat-SA exhibits excellent antibacterial activity, cytocompatibility, and hemocompatibility. These advantages of QCS/Cat-SA, including strong blood clotting, wet tissue adherence, antibacterial activity, biosafety, ease of use, and stable storage, make it a promising hemostatic agent for emergency situations.