Powder molded compacts, characterized by low powder filling rates such as Metal Injection Molding (MIM), often exhibit problems with deformation during sintering due to their large shrinkage and low strength. In this study, the Digital Image Correlation method (DIC) was used for in-situ observation of sintering in Ni powder compacts fabricated by MIM to investigate their large-deflection deformation behavior. As a result, it was revealed that there is a time point when the deviatoric vertical strain in the longitudinal direction becomes tensile across the entire base of the molded compacts. This strain distribution was not symmetrical distribution of tensile and compressive strains, as is typically observed in the small deflection deformation of an elastic body. Additionally, a finite element analysis was performed using a plastic deformation model for porous materials, and it was confirmed that similar results were obtained.

Austenitic stainless steel SUS304L and SUS316L are used in exterior parts of watches and clocks from the viewpoints of mirror-like surface and corrosion resistance. The austenitic stainless steel contains about 10 to 14 mass% Ni, which is a cause of metal allergy, and there has been a demand for Ni-free stainless steel that does not affect human skin while maintaining mirror finish and corrosion resistance. In sintered compacts made using the metal injection molding method, a dense layer with no inclusions is formed only 50 to 100 µm from the surface layer. Therefore, even if they are polished, microscopic pores are present on the surface, and a high-quality mirror-like surface couldn't be obtained. In this study, we investigated fabrication that reduces inclusions from the surface layer of Ni-free stainless steel and evaluated characterization of the sintered compacts.

The austenitic stainless steel used for the exterior parts contains Ni, which causes metal allergies, so there was a need for a Ni-free stainless steel. On the other hand, ferritic stainless steel does not contain Ni in its alloy, so it does not cause metal allergies, but it is said that its corrosion resistance is inferior than austenitic stainless steel because of a weaker passive film.In addition, the sintered compacts producted by metal injection molding have micropores inside, so their corrosion resistance are lower than the wrought, and they are susceptible to scratches because of a low hardness of 180 to 200 Hv. Therefore, we conducted research to improve both the corrosion resistance and hardness of sintered compacts using the water-atomised ferritic nickel-free stainless steel powder by MIM, which can produce near net shape parts.

Stellite is an alloy consisting mainly of Co with additions of Cr and W. It has excellent heat and wear resistance but is generally finished by machining after casting because it is very difficult to machine. In this study, the effects of sintering conditions on the microstructure and mechanical properties of Stellite6 alloy fabricated by the metal injection molding process were investigated. The injection-molded compacts were sintered in a vacuum at temperatures between 1225°C and 1275°C and holding times of 135 minutes. The microstructure of the sintered alloys consisted of Co, Cr carbides, and Cr oxides. The tensile strength and elongation of the alloy were 1225MPa and 14% at a sintering temperature of 1250°C.

Metal Injection Molding (MIM) is an advanced manufacturing technique that integrates the methodologies of plastic injection molding and powdered metallurgy. The MIM process is used in aerospace, medical devices, and automotive industries to produce high-precision complex three-dimensional components. In this study, IN718 alloy was fabricated using the MIM process, and its microstructure, and high-temperature mechanical properties were analyzed and compared with Selective Laser Melted (SLM) IN718 alloy specimens in as-built and heat-treated conditions. Tensile testing revealed that the yield strength of MIM IN718 was similar to that of SLM IN718 in the as-built condition. However, in the heat-treated condition, the yield strength of MIM IN718 was significantly lower than that of the SLM specimens. Additionally, the ductility of MIM IN718 was found to be considerably inferior to that of SLM IN718 in both conditions. This reduction in yield strength and ductility in MIM IN718 was primarily attributed to the formation of Al₂O₃ due to oxygen contamination. The Al₂O₃ acted as heterogeneous nucleation sites for brittle Nb-rich carbides, which served as crack initiation points. Furthermore, the presence of these Al₂O₃ particles and Nb-rich carbides suppressed the formation of the γ′/γ′′ strengthening phases by consuming the necessary forming elements, thereby reducing the overall strength of the material.

Powder magnetic cores used in reactors are required to have low iron loss, and alloy materials are used as low iron loss powder magnetic core materials. However, powder cores made from alloy materials have the issue of low strength, so we have been investigating the method of adding low-melting-point glass powder to improve strength. Although the strength of powder cores improved when glass powder was added, it significantly worsens iron loss, and we found that the sodium contained in the glass cause it. The sodium contained in the glass destroys the insulating coating of metal particles, which is one of the factors that increases iron loss when glass is added.

Magnetoliposomes (MLs), which combine liposomes (LPs) and magnetic nanoparticles (MNPs) as a composite, exhibit multifunctional properties as theragnostic and biosensor tools. In most biosensor applications, magnetic functions in MLs are used only for magnetic separation owing to the attraction force between MNPs and a permanent magnet. The present paper reports MLs as a magnetic sensing label based on magnetic analysis in liquid through alternating current susceptibility measurements. The MLs must contain a larger amount of MNPs in the membrane structure to obtain a larger magnetic signal. We systematically compare dynamic magnetic properties of MLs synthesized by two synthesis methods. The MLs synthesized by the double emulsion method contain more MNPs in the core of unilamellar LPs and generate a larger magnetic signal compared with that by the thin film hydration method. The magnetic relaxation behavior depends on the hydrodynamic behavior of both MLs and encapsulated MNPs.

Soft magnetic composites cores (SMC cores) were prepared by compacting developed insulated pure iron powder. Their iron losses in both sinusoidal excitation and inverter excitation were evaluated. Compared to stacked cores made of commonly used electrical steel sheets, the SMC cores show lower eddy current losses, and exhibit lower iron losses than the stacked cores at frequencies above approximately 1 kHz under sinusoidal excitation, and above approximately 400 Hz under inverter excitation. Next, a prototype axial gap motor was designed by electromagnetic field analysis based on a commercially available radial gap motor as a model. The prototyped axial gap motor has achieved a 48% reduction in its axial length and a 40% reduction in its weight.

Our Fe–Mn–Ni soft magnetic powders have the potential to be applied to axial-gap motor stators and high-frequency transformer cores owing to their low coercivity and saturation magnetization equal to or higher than that of pure iron. Fe–Mn–Ni soft magnetic powders were fabricated by the reduction of Ni–Mn doped ferrite nanopowders with hydrogen gas at 1323 K. The magnetic powder cores were fabricated form Fe–Mn–Ni soft magnetic powders coated with the novel phosphate insulators containing various metals. Our group has developed a novel phosphate coating technology with improved thermal stability for iron-based alloy powders. Moreover, we investigated the effect of Ni–Mn doped nanoferrite on the magnetic properties of Fe–Mn–Ni soft magnetic powders and the high-frequency properties and structure of insulating phosphate layer containing various metallic elements coated on Fe–Mn–Ni alloy powders. The addition of several metals improves the highfrequency properties, resulting in an iron loss of 26.2 W/kg at 1 T and 400 Hz and a magnetic flux density of 1.64 T at 10 kA/m owing to the combination of rare-earth elements and transition metals.

Electrification pushes the agenda of soft magnetic material development, with increased demands on efficient low loss materials with minimal environmental impact. Soft Magnetic Composites (SMC) challenges traditional magnetic materials such as soft ferrites and electrical steels in applications with alternating magnetic fields, and can many times offer a solution that is more efficient and with lower carbon footprint. In comparison to those traditional materials, however, the relatively higher hysteresis has so far limited wide application of SMC. This paper presents a new material which combines an improved base powder and a newly developed water-based coating, into a product with lower hysteresis losses than any previous SMC material, combined with improvements in processing and application.This paper introduces Somaloy^® 7P, discusses the effect of manufacturing process parameters, such as compaction, heat treatment atmosphere, on component performance. Furthermore, the effects of operating temperature on component properties are investigated.

The intensifying electrification trend in the automotive industry along with calls for high-efficiency, low-cost industrial applications drive the demand for energy- and cost-efficient electromagnetic components. Electromagnetic components of soft magnetic composite (SMC) materials can play an important role in this trend, making it possible to manufacture more compact and cost-efficient motor and inductor solutions compared to using traditional designs. SMC materials are made of iron powder particles coated with an electrically insulating layer and can be formed into complex shapes by means of powder metallurgy (PM), thereby allowing three-dimensional magnetic circuit design.This study mainly evaluates and analyses a partial carbon footprint of a product (CFP), applied to SMC powder production including raw materials, atomizing, annealing and surface insulation coating. Some life cycle analyses (LCA) of component manufacturing and benefit in electromagnetic application are also presented. Finally , a primary investigation to recycle SMC part is reported in this study.

Additive manufacturing (AM) processes are using powders with different particle size distributions. However, a significant fraction of metallic powders produced for AM do not have the appropriate particle size distribution to be used in AM processes. Consequently, high-quality powders are out of AM specifications and cannot be used in AM processes. This directly impacts the cost and sustainability of many AM processes. There are opportunities to adapt and develop processes to take advantages of the fine microstructures of these rapidly solidified powders. This presentation provides examples of microstructure and properties of materials produced using AM by-products. The effect of the particle size and consolidation techniques on the properties of the materials is presented and discussed.

Current methods for the production of spherical powders restrict the development of new chemical compositions dedicated to the additive manufacturing industry. This novel ultrasonic atomization process enables in-house powder production from even one gram up to a few kilograms to verify new alloys. The technology uses vibrations to break the surface tension of liquid metal to allow atomization. To melt the material plasma torch or induction heating can be used allowing to process wide range of metals. Plasma-based ultrasonic atomization was used to manufacture spherical powder of a high-temperature alloy, while induction-based ultrasonic atomization was used to develop a low-melting alloy. Additional case study of recycling titanium alloy maching chips into the powder by arc melting and ultrasonic atomization is presented.

The primary obstacle for laser powder bed fusion (LPBF) is the high cost of feedstock materials. Powder reuse in LPBF is one of the most important strategies to reduce the cost. However, the oxygen content in the powder feedstock would increase with reuse. It is necessary to understand the relationship between the oxygen content and the part qualities of the LPBF products. In this study, Ni-Cr-Mo-based alloy feedstocks with different oxygen contents were prepared to evaluate the effect of oxygen on the part quality during powder reuse. It was revealed that the oxygen content did not affect the strength, hardness, and corrosion properties of the LPBF Ni-Cr-Mo-based alloy; however, it affected the elongation in tensile test.

Steel swarf generated from the machining and polishing of steel tools can be recovered, cleaned, milled, and magnetically separated into a powder suitable for processing via field assisted sintering. Field assisted sintering, when combined with thermal post-treatments, has the potential to directly generate tools, such as cutting disks, from this recovered swarf. The attractive features of this technique include the ability to generate metal matrix composites, the utilization of unconventionally shaped powder, and the avoidance of the high energy cost of re-melting. The possibilities of this technique are explored using a high carbon and high chromium steel swarf, AISI D2, produced industrially and recovered for direct recycling to contribute to a circular economy.

Global lithium demand is expected to increase from 500,000 tons in 2021 to 2 million tons in 2030, and the lithium shortage is expected to reach 220,000 tons. This dramatic increase in lithium demand is largely due to the widespread use of lithium ion batterie, or electronic devices. In recent years, there has been a global effort to extract lithium ions from dissolved seawater or wastewater. We also developed a lithium extraction system consisting of an anion exchange membrane (AEM) and lithium lanthanum titanium oxide (LLTO) membrane. The system produced lithium concentrated solutions with a lithium ion concentration of 10,000 ppm and a lithium selectivity (Li⁺/Mg²⁺) of 1000. Lithium phosphate powder with 99.5% purity was fabricated from lithium concentrated solution through a powdering process. Its purity is such that it can be used in industry and is expected to have a wide range of applications.

The surge in electric vehicles and E-mobility markets is boosting secondary batteries, particularly lithium secondary batteries known for exceptional performance. With global demand rising due to electric vehicles taking center stage for carbon neutrality, the focus on environmental impact and CO₂ emissions from fossil resource use intensifies. The growing quantity of end-of-life electric vehicle batteries poses a global recycling challenge. This study explores a Pyrometallurgical Process for lithium hydroxide recovery from Waste lithium-ion batteries (LIBs) black powder. Optimized thermal treatment removes impurities, and Self-propagating High-temperature Synthesis (SHS) using Mg as a reducing agent effectively isolates lithium as lithium oxide (Li₂O). Thermodynamic calculations with HSC Chemistry software reveal the mechanism behind lithium oxide recovery. Recovered lithium oxide undergoes optimized water treatment for enhanced lithium hydroxide recovery efficiency. The properties of the recovered lithium hydroxide are assessed through various analyses, including XRD and ICP.

Porous ceramics based on mullite was fabricated using the superplastic foaming method we proposed. When mullite powder was used as the starting material, the porosity was less than 20%. A compacted body was obtained from the constituent metal oxides and the porous body obtained by reaction sintering had a porosity of nearly 50%. The spinel phase and excess silica formed before the formation of mullite were effective in promoting grain boundary sliding and increasing porosity. Additionally, the addition of titania increased the mullite formation temperature, which increased the foaming time and increased the porosity. The obtained mullite-based porous material exhibited strength and thermal conductivity comparable to that of 3YSZ (3 mol% yttria stabilized zirconia) at the same porosity level. Mullite has significant advantages over 3YSZ in terms of cost and creep resistance.

The SPS method was used to sinter zirconium powder mixtures. Materials were prepared from pure zirconium powder and mixtures with 2.5 wt% additives of Cu, Nb or Mn powders. The influence of hydrogen and oxygen on the phase compositions of sintered materials are presented. Based on the studies of oxidized materials microstructures, degradation mechanisms of sintered zirconium materials were analyzed for materials after annealing at 300, 500, and 700 °C. Zr-2.5Cu showed the lowest tendency to oxidize despite the low values of activation energy for the oxidation process in air of 61 kJ/mol. The tensile strength tests of the sintered zirconium materials were carried out at 300 °C, 500 °C and 700 °C. Porosity mainly affects the mechanical properties of sintered zirconium materials.

This study investigated the effect of heat treatment temperatures on the microstructure and mechanical properties of MA6000 alloy, produced via spark plasma sintering. The MA6000 alloy, enhanced with Fe, Mn, Zr, and Y₂O₃ additions for improved heat resistance, underwent heat treatments at 1000°C, 1100°C, and 1200°C. Results show that at 1000°C, the original microstructure was maintained with minimal grain growth, while at 1200°C, significant recrystallization occurs, leading to new grain formation and distinct grain boundaries. Relative density and porosity remained stable at approximately 98% and 0.5-0.9% respectively up to 1100°C. However, at 1200°C, relative density increased to 99.2% and porosity decreased to 0.1%, indicating a highly densified structure. Hardness decreased significantly from 582 HV to 410 HV with increasing annealing temperature, suggesting the need for balanced heat treatment conditions to optimize material properties. XRD analysis revealed the formation of protective Cr₂O₃ layers at 1000°C and 1100°C, while at 1200°C, the presence of Fe₃O₄ indicated higher oxidation levels, although the primary Ni phase remained unoxidized. These findings highlight the importance of heat treatment in adjusting the microstructural and mechanical properties of MA6000 alloy, providing valuable insights for optimizing its performance in high-temperature applications.

ZrB₂ is a leading candidate for TPS for re-entry vehicles due to its high melting point, thermal shock resistance, and low density. ZrB₂ does not fully possess oxidation resistance necessary for surviving the re-entry condition. It improves oxidation resistance when composited with SiC and can withstand the intense oxidation environment caused by aerodynamic heating during re-entry. In order to develop TPS, high-density ZrB₂-SiC with different composition ratios were fabricated by the spark plasma sintering (SPS). In this research, ZrB₂-SiC and related materials of UHTC, TiB₂-SiC and TiC-ZrC, were fabricated by SPS and oxidation behavior was evaluated.

In this study, Ti-6wt%Al-4wt%Dy and Ti-6wt%Al-4wt%V were prepared by high energy ball milling and spark plasma sintering(SPS). A high energy ball milling was conducted in an argon atmosphere at 800rpm for 3h to produce alloy powders. Subsequently, the obtained powders were consolidated by SPS at 1373K for 15min under 50MPa in vacuum. The sintered bodies of Ti-6Al-4Dy and Ti-6Al-4V both had an approximate density of 99%, with grain sizes of 6μm and 2.6μm, respectively. In Ti-6Al-4Dy, secondary phases such as Ti₃Al, Al₃Dy, and Ti₄Al₂₀Dy were confirmed by XRD and TEM. In Ti-6Al-4V, only the alpha phase of Ti was confirmed. At temperature ranging from 300K to 1173K, the micro hardness of both Ti-6Al-4Dy and Ti-6Al-4V alloys decreased with increasing temperature, and the Ti-6Al-4V was harder at all temperatures. XRD analysis of Ti-6Al-4Dy and Ti-6Al-4V revealed no discernible changes in peaks after high temperature hardness test. However, the grain size increased from 6 to 10μm and 2.6 to 3.4μm in Ti-6Al-4Dy and Ti-6Al-4V alloys, respectively. It was concluded that this difference in grain size was the main reason for the hardness decreased at high temperature.

High-temperature applications require materials that balance stiffness, strength, ductility, and corrosion resistance. Traditionally, Ni-based superalloys have been used to fulfil this role since they are the most suitable. A new research window opened up when a stable reinforcement phase was discovered in a Co-Al-W system. The present research aimed to lower density while increasing working temperatures. To achieve this, spark plasma sintering (SPS) was used to manufacture three low-density Co-based superalloys, which were then homogenized and aged to improve the performance at high temperature. Microstructure was characterized to understand the mechanical behaviour tested by hardness and by compression tests, carried out at different temperatures.

Thanks to its high electrical conductivity, durability and malleability, copper is widely used for EV and for electronic components. EV use more than double the copper of an internal combustion engine automobile and it is also used heavily in EV-infrastructure like charging stations and in electrical grid infrastructure. Sintered Copper components could be part of the transition from combustion to electric engine and EV revolution. Pometon, by the experience on production of ECP and WA copper, continues to develop improved ready to press products to meet the needs of the classical sintering production process for the fabrication of copper components.

This new study shows the developing of a high purity and highly densifying copper powders in particular improving the usage of the Premixes (flowability, compressibility and dimensional changes) and the conductivity of the sintered parts to obtain the chemical, physical and mechanical characteristics needed for E-automotive and electronic applications.

Biometals for medical implants are required to have both low stiffness and high strength, and porous titanium(Ti) is expected for such biometals. Although porous Ti exhibits low stiffness, its application to the implants may be limited because of low strength. Improvement of the strength of porous biometals could be achieved by strengthening their scaffold metals. In this study, the feasibility of using Ti-Zr alloys as a scaffold material for porous biometals is investigated. Ti and Zr powders mixed in various volume fractions are simultaneously sintered by spark plasma sintering. As a result, the Ti-25Zr alloy exhibits the highest bending strength in the fabricated Ti-Zr alloys including pure Ti, indicating that the Ti-25Zr alloy is suitable as a scaffold of porous biometal.

Extensive research on titanium alloys is being developed to enhance its mechanical properties, particularly for biomedical and aerospace engineering applications. Commercially Pure Titanium (CP-Ti) is a reference in these fields; however, its inherent limitations, such as moderate wear resistance, lead to the exploration of novel alloys. This study focuses on the production of a beta Ti-13Ta-6Sn alloy through high-energy milling, aiming to surpass the wear performance of CP-Ti while maintaining biocompatibility. The alloy's microstructure, phase composition, corrosion resistance, and mechanical properties were characterized. Compared to CP-Ti, the alloy exhibited a lower elastic modulus and higher yield strength. Tribological and microhardness evaluations revealed an order of magnitude lower wear rates and higher strength, highlighting the potential of this alloy in mitigating wear-related challenges.

Owing to their excellent wear and corrosion resistance and their good mechanical properties, nickel aluminium bronze alloys (NABs) are ideal materials to manufacture components of marine industry. In this work, NABs with nominal composition Cu-10Al-5Ni-4Fe-1Mn (wt.%) were obtained following advanced manufacturing technologies based on powder metallurgy, like press and sintering and HIP. The influence of processing conditions during sintering, HIPing and final heat treatments on the final microstructure is evaluated. Mechanical properties (hardness, tensile and Charpy impact tests) as well as corrosion and erosion-corrosion resistance are also presented. It has been found that an adequate selection of the starting powders and sintering and HIP conditions leads to dense materials. Final heat treatments are responsible for further microstructural refinement and dissolution of detrimental brittle phases, like martensitic β or coarse rosette κI, resulting in enhanced mechanical strength and resistance to erosion-corrosion in seawater, as compared to conventional cast NABs.

The morphology and distribution characteristics of reinforcements in titanium matrix composites (TMCs) play a crucial role in determining their final performance. To address the issues of uncontrollable morphology and inhomogeneous distribution of reinforcements, a series of core-shell-structured C-coated Ti powders were developed using a fluidized bed powder-coating approach. This technique maintains the inherent structural nature of C-coatings, enabling reinforcements to be tailored by creating various reaction paths, including in-situ retention of C sources, Ti-C interfacial reaction, and dissolution-precipitation reactions. Intragranular and interfacial reinforcements with distinct morphologies were synthesized by combining different C sources with suitable powder-forming strategies. This study briefly summarizes our recently experimental findings and achievements in preparing TMCs strengthened by various reinforcements, and elaborates the influence of morphology and spatial distribution on the strengthening efficiency of reinforcements. These fundamental outcomes are anticipated to provide insights into fabricating high-performance TMCs by tailoring reinforcements based on basic powder materials.

Increasing yield strength of Ti by utilizing dispersive second-phase particles that impede dislocation motion is one of the most common strengthening methods. However, an improvement in strength will inevitably sacrifice ductility in dispersion-strengthened titanium matrix composites. Our group has developed a brand-new interdiffusion and self-organization strategy, resulting in pelleted hetero-structure Ti6Al4V-TiBw composites with both non-uniform distribution reinforcements and heterogeneous grain structures by utilizing the interdiffusion reaction between alloying elements and titanium. It was found that the pelleted hetero-structure Ti6Al4V-TiBw composite exhibits a remarkable 11.5% elongation, comparable to Ti6Al4V alloy, while significantly improving its strength. The good fracture elongation mainly comes from the HDI hardening effect produced by the heterogeneous grain structure of matrix and the blunting and deflection effects of the heterogeneous distribution of TiBw reinforcements on cracks. Our strategy can be applied to other composite systems for developing high-performance metal matrix composites with harmonious strength and ductility.

In this study, gas atomization can be used to prepare spherical NdFeB powders or thin flakes. The SEM micrograph of the NdFeB powders can be seen that all of the alloy powders are spherical and had smooth surfaces. The median particle size distribution D50 is about 25μm. The XRD of the thin NdFeB flakes are well indexed to the Nd₂Fe₁₄B phases with the prefer grain growth direction of the Nd₂Fe₁₄B phases. The NdFeB powders which prepared by gas atomization process can be potentially used for additive manufacturing applications. This study also demonstrated that well optimized gas atomization technique can be used to prepare highly oriented thin NdFeB flakes without using traditional strip-casting process.

Additive manufacturing through materials extrusion is recognized as a promising method for scaffold fabrication, thanks to its affordability, versatility, and widespread applicability across various materials. Achieving the desired properties in tissue engineering necessitates a reliable and controllable printing process. In this study, analytical models have been formulated to simulate the geometric features of cylindrical polycaprolactone (PCL) scaffolds manufactured through materials extrusion-based additive manufacturing, employing principles of fluid mechanics. The geometric attributes of the PCL scaffold can be anticipated by considering extrusion pressure, temperature, nozzle diameter, nozzle length, and printing speed. To validate the effectiveness of the models, they are compared against experimental results. The simulation outcomes reveal a robust correlation between geometric characteristics and processing parameters, highlighting the utility of the developed models in predicting the scaffold structure's geometric features in materials extrusion-based additive manufacturing.

The affinity of partially hydrophobic silica nanoparticles for organic solvents (ethanol and hexane) was characterized using changes in relaxation time obtained from time-domain nuclear magnetic resonance (TD-NMR). Different chain lengths (C3, C6, and C12) were used as surface modifiers for the particles, with the modification ratio controlled. For ethanol, longer chain lengths and higher modification ratios resulted in higher affinity. Conversely, for hexane, the affinity was generally poor under all conditions, but shorter chain lengths and lower modification ratios showed higher affinity. We hypothesize that ethanol molecules are attracted to residual silanol groups among long-chain length functional groups. To test this hypothesis, we investigated the affinity of the partially hydrophobic silica nanoparticles in an ethanol/hexane mixture. In the range of 60 to 80 vol% hexane, the relaxation time of the C12-modified silica nanoparticles (with a modification ratio of 1.4/nm²) quickly decreased. This decrease disappeared when the residual silanol was additionally modified with C3. TD-NMR has proven to be an effective tool for detecting changes in surface affinity of partially hydrophobic nanoparticles, even when they exhibit the same hydrophobicity.

Additive manufacturing of ceramic/metal composites combines the material's advantages with the flexibility of 3D printing, allowing the customized production of complex structures while enhancing lightweight design outcomes. Currently, this technology is widely employed in sectors such as aerospace and automotive for processing and manufacturing high-performance components. In this study, we developed a material extrusion 3D printing system for metal-ceramic hybrid structures. The system facilitates low-heat printing, and the printed samples can be easily and safely debound using an alcohol-based process, greatly simplifying the process flow and improving the processing efficiency of high-performance composites. Furthermore, as part of this research, 3D printed composites of SUS316L/ZrO₂ were developed to fabricate intricate structural workpieces.

Laser powder bed fusion (L-PBF) is a metal additive manufacturing (AM) technique that utilizes high-power laser to selectively fuse metal powders, in a layer-by-layer manner, to create a 3D object. After LPBF process, there are often a substantial quantity of powders that is left unused. If the powders are not recycled, it becomes not cost-effective; however, directly reusing the used powders compromises the printed part quality. Therefore, we explored the feasibility of producing high-quality pre-alloyed FeCoNi powders through mechanical pre-alloying and plasma atomization of recycled elemental Fe, Co, and Ni powders. Extensive characterizations such as porosity, hardness, tensile, micrography, and chemical distribution were carried out to investigate the produced powders and the AM parts fabricated using them. It is revealed that the processed recycled powders showed markedly less defects than their as is condition. Through such approach, the sustainability for metal additive manufacturing and cold spray techniques can be significantly improved.

Hematite α-Fe₂O₃, called “bengara”, is widely used as a red pigment because it is abundant, economical and extremely low in toxicity. However, its redness is not so high at around a*=+30. In this study, we attempted to improve the redness by controlling the microstructure of iron oxide particles and adding the Al element. To achieve this goal, we focused on fibrous hematite particles. The synthesis of fibrous particles was carried out by the co-precipitation method. That is, ammonium was dropped into a mixed aqueous solution of iron chloride and aluminum chloride, and the mixture was adsorbed and precipitated on phosphorylated cellulose nanofibers (P-CNF). By heat-treating the precipitate, the P-CNF was burned and at the same time the hydroxide precipitate crystallized into hematite while maintaining the fibrous shape. The sample with 23% Al added showed an excellent reddish yellow color with a*=42, b*=52, and L*=50 after heat-treatment at 800°C.

The chemical vapor synthesis process is a widely used method for producing the powder for the electrode layer in electronic components such as multilayer ceramic capacitors. This process utilizes solid metal chloride as a precursor. The metal chloride is vaporized and then reduced with a reducing gas, such as hydrogen, to form metal powder. A common issue in this process is the unintentional introduction of moisture into the reactor along with the metal chloride powder precursors. This moisture can lead to unintended side reactions. To address this issue, our study conducted a thermodynamic analysis of the side reactions caused by moisture in the reactor. We experimented by injecting HCl gas, a by-product of these reactions, and observed the impact at different partial pressure ratios. This research aids in comprehending and potentially preventing the detrimental effects of moisture in chemical vapor synthesis.

Proton Exchange Membrane (PEM) Electrolyzers are key to green hydrogen production, reducing reliance on nonrenewable energy and cutting carbon emissions. A critical component, Gas Diffusion Layers (GDLs), facilitates transport processes and provides structural support. This study enhances GDL efficiency through powder metallurgy, examining fine, large, and Gaussian-distributed powders using the GeoDict simulation tool. Findings reveal that fine particles offer better mechanical properties but reduced flow capacity, while large particles improve flow but weaken mechanical strength. The Gaussian distribution, with varied particle sizes, is identified as optimal for producing porous GDLs. This research advances efficient GDL development, promoting sustainable hydrogen production.

A novel fabrication method for manufacturing tubular micro-filtration membrane with mirror-like surface by one step co-sintering without additive doping has been developed. The surface morphology, pore distribution and permeability performance are studied, which supplies a theoretical basis for the preparation of low-cost metallic membrane and further study their pore evolution mechanism. The result shows that the metallic membrane was bonded to the support tightly after sintering at 1250℃ for 2h. The fine powder content has a significant impact on the integrity of the membrane layer, which is due to the synergistic shrinkage during the co-sintering process. The surface roughness and average pore size of the as-fabricated stainless-steel membranes by the new method are 178 nm and 2.1 μm, respectively.

This paper presents a study on T15 high-speed steel produced through conventional and powder metallurgy (PM) methods, which involved electroslag remelting (ESR), hot isostatic pressing (HIP), and forging. The samples are heat-treated to achieve various grain sizes, types and volume fractions of carbides by quenching temperature ranging from 1180 °C to 1220 °C and tempering at 560 °C. The microstructure was characterized using scanning electron microscopy (SEM), and x-ray diffraction (XRD). Mechanical properties including hardness, bending strength and fracture toughness are assessed. The improvement in mechanical properties associated with microstructural characteristics for different processes is compared and discussed. The current work provides a multifaceted process perspective for the preparation and comparison of high-speed steel.

This study develops an eco-friendly non-destructive testing method for powder metallurgy, aiming to improve inspection techniques like magnetic particle inspection, given environmental impacts. The primary goal is to establish an intelligent manufacturing-based AI system for detecting internal cracks in powder metallurgy components after sintering. Acoustic data is collected using an electric hammer and microphone after sintering and processed to create spectrograms. An autoencoder extracts features, followed by cluster analysis to select samples for destructive testing. By integrating audio recognition technology and a convolutional neural network (CNN), unique sound features of sintered materials are identified, achieving a remarkable 99.60% accuracy in identifying specific types of powder metallurgy products. This eco-friendly testing method aligns with green manufacturing and showcases AI's potential in powder metallurgy manufacturing. This study demonstrates a significant advancement in enhancing quality control and propelling the powder metallurgy industry towards environmentally friendly manufacturing practices.

The steel bonded carbide/Q235 steel composite wear-resistant plate was prepared by vacuum sintering to address the problems of insufficient wear resistance of single steel wear-resistant plates, poor impact resistance and limited thickness of wear-resistant layer of hardfacing wear-resistant plates. The effects of sintering temperature on the microstructure and properties of the composite plates were explored. The results showed that there was a layer of mutual dissolution zone at the interface. Diffusion of C, Mn and Ni atoms resulted in a metallurgical bond. With the increase of the sintering temperature, the width of the mutual dissolution zone increased significantly, the microhardness increased first and then decreased. Meanwhile, the interfacial shear strength decreased gradually, the impact toughness increased first and then decreased.

Titanium (Ti)-zirconia (ZrO₂) bonded materials have been developed as biomaterials with superior hardness, excellent wear resistance, and robust mechanical properties. However, it is crucial to investigate the Ti/ZrO₂ interfacial microstructure and suppress the formation of Kirkendall voids caused by elemental diffusion at the bonding interface. This study aims to investigate the effect of oxidation treatment on suppressing elemental diffusion at the interface between pure Ti and ZrO₂. Prior to sintering, the titanium surface was oxidized by supplying oxygen gas at a rate of 10 liters/min at 800, 900, and 1000°C for different periods of time. It was studied the effect of the temperature and the holding times during the oxidation treatment of Ti substrate. The Ti/ZrO₂ sintered bonds were prepared using the spark plasma sintering process. The microstructures at the bonding interface were observed using SEM. The oxidized titanium surface was analyzed using X-ray diffraction, and elemental diffusion behavior was assessed through EDS analysis. The results demonstrated that elemental diffusion at the interface can be effectively suppressed when oxidation is carried out at temperatures above 900°C for extended periods.

The purpose of this study is to evaluate the compressive strength of sintered titanium porous materials and their composites with biopolymers. The sintered porous material exhibits a network morphology due to the contact between particles connected in three dimensions. Titanium alloy powder (Ti6Al4V) was used as the raw material, and the powder was sintered using the spark plasma sintering process at a temperature of 750°C. Three types of biopolymers—polylactic acid, chitosan, and a chitosan derivative—were impregnated into the porosities of the sintered porous materials to produce the composites. To predict the compressive proof stress, the Gibson-Ashby formula was modified for these materials. This prediction of compressive strength is based on relative density in relation to porosity and relative compression strength measured experimentally. Compression tests were performed, and the proof stress was calculated. All experimental data were represented by prediction-fitting curves derived from the modified equation. The compressive strength characteristics of the porous Ti6Al4V alloys were clarified, and measurements of bending strength and tensile strength were conducted. The results were compared with the strength characteristics of bone, suggesting the potential applicability of the material as an implant.

The Copper (Cu) - Titanium (Ti) powders with varying of Ti content(0.3, 0.5, 1, 2, 4, 6, 8 wt.%) were mixed using a horizontal ball milling. The milling process was performed for 6 hrs at 300 rpm. The Cu-Ti composites were fabricated by a spark plasma sintering process at a sintering temperature of 850℃ and heating rate of 30 ℃/min under a pressure of 40 MPa. The relative density of the composites was all densified to more than 99%. The Cu and Ti in the Cu matrix are unstable to exist in a single phase at temperature range of 800-875°C and a Ti content of 4-8 at.% (3.04-6.15 wt.%). Thus, each element is stabilized by forming a secondary phase. The phase of Cu₃Ti was detected upon the Ti content was 4 wt.% or higher, which affected the thermal properties. The thermal conductivity decreased from 262.74 to 46.10 W/m·K according to increase the Ti contents. The Ti present in the heat transfer path in Cu matrix acted as an obstacle to heat diffusion. Furthermore, as the Ti contents increased, the Vickers hardness of Cu-Ti composite increased from 60.19 to 205.20 kg/mm². In contrast, the crystallite size decreased from 66.63 to 22.43 nm. The Ti particles suppressed the grain growth of the Cu matrix, resulting in a decrease in crystallite size, which contributed to the improvement of the mechanical properties.

The spherical type of aluminum (Al) was mixed with (20, 30, 40, 50, and 60 vol.%) flake type of graphite (G_f) using a shake mixer at 2,500 rpm for 1 hr. The Al-G_f mixed powders were consolidated by spark plasma sintering under the following process conditions; sintering temperature of 480°C with heating rate of 60 °C/min, sintering pressure of 40 MPa and duration of 2 minutes at the temperature of 480°C. The results showed that the Al-20 vol.% G_f sintered-body achieved highest relative density of 98%, while the lowest value was 92% when the G_f content was 60 vol.%. The porosity rate, measured using ImageJ, ranged from 2.0 to 8.5% as the G_f content increased. The decrease in relative density was attributed to the formation of pores at the Al-G_f interface. This was due to the increased G_f content that is stable at high temperatures and the poor wettability between Al and G_f. The thermal conductivity of the composites increased from 198 to 340 W/mK as the G_f content increased. However, the thermal conductivity of the Al-60 vol.% G_f composites was 260 W/mK due to the higher porosity and orientation of G_f. In conclusion, the increase in G_f content in the Al-G_f composites led to a decrease in relative density because of pore formation. Nevertheless, the thermal conductivity of the composites generally increased with increasing G_f content, except for the Al-60 vol.% G_f composite, which exhibited lower thermal conductivity due to the higher porosity.

High-strength Cu/Al₂O₃ composites usually exhibit obviously deteriorated electrical conductivity when compared with their low-strength counterparts. In this work, a chemical and mechanical alloying-based strategy was adopted to fabricate an ultrafine composite powder with low-content reinforcement and construct a combined structure of Cu ultrafine powders covered with in-situ Al₂O₃ nanoparticles. After consolidation at a relatively lower sintering temperature of 550 ℃, high-volume-fraction ultrafine grains were introduced into the Cu/Al₂O₃ composite, and many in-situ Al₂O₃ nanoparticles with an average size of 11.7±7.5 nm were dispersed homogeneously in the Cu grain interior. As a result, the composite showed an excellent combination of high tensile strength (654±1 MPa) and high electrical conductivity (84.5±0.1% IACS), which was ascribed to the synergistic strengthening effect of ultrafine grains, dislocations and in-situ Al₂O₃ nanoparticles. This approach using ultrafine composite powder with low-content reinforcement as a precursor followed by low-temperature and high-pressure sintering may have the potential to be applied to large-scale industrial production of high-performance oxide dispersion strengthened alloys.

Insulated ferromagnetic particles with inorganic layer allow heat treatment at relatively high temperatures, which improves the magnetic permeability and hysteresis loss behavior of SMCs. However, as the particle core is more susceptible to plastic deformation than the insulating coating, the electrical insulation can be damaged during the compaction process. Such insulation breakage leads to more intense eddy currents, which reduces the SMC performance due to higher dynamic losses. This work addresses a solution to this well-known problem by completely generating the insulation between iron particles in a post-compaction heat treatment by combining two classes of precursors: carbon-based oxygen carriers (hydrothermal carbon spheres and graphene oxide) and boric acid. The synergistic mechanism of this double-layer SMC resulted in a reduction in dynamic losses of up to 61% compared to single-layer SMC. The results also indicate that precursors with a high surface to volume ratio can maximize this material magnetic performance.

The temperature dependence of the magnetostrictive properties of Cu_0.6Co_0.4Fe₂O₄ and CoFe₂O₄ samples was investigated. At 300 K, the strain magnitude of the Cu_0.6Co_0.4Fe₂O₄ sample increased with increasing magnetic fields and reached a maximum value at approximately 0.8 T. Upon further increasing the magnetic fields, the strain magnitude gradually decreased and almost saturated at 7 T. Compared to the CoFe₂O₄ sample, the Cu_0.6Co_0.4Fe₂O₄ sample exhibited a more pronounced increase in the strain magnitude as the temperature decreased. In addition, the strain magnitude at 7 T of the Cu_0.6Co_0.4Fe₂O₄ sample exhibited a clear maximum at 100 K, unlike that obtained of the CoFe₂O₄ sample. The Cu_0.6Co_0.4Fe₂O₄ sample showed a strain of approximately 911 ppm at 100 K by changing the direction of 7 T magnetic field, which is significantly larger than that of the CoFe₂O₄ sample. Thus, the Cu_0.6Co_0.4Fe₂O₄ sample showed a larger strain magnitude than the CoFe₂O₄ sample in the temperature range of 10–300 K. Therefore, the partial substitution of Cu for Co is very effective in enhancing the magnetostrictive properties of CoFe₂O₄ across a wide temperature range, including room temperature.

The relationship between crystal structure and magnetostrictive properties of Cu_0.8Co_0.2Fe₂O₄ was investigated. Although the as-synthesized Cu_0.8Co_0.2Fe₂O₄ sample showed a tetragonal spinel structure, a cubic spinel structure was obtained by heating at 1033 K and subsequent quenching. The as-synthesized sample was strained moderately by the application of magnetic fields. The magnetic field dependence of strain magnitude showed moderate changes without a saturation below 2.4 T. On the other hand, the sample quenched from 1033 K strained more sensitively by the application of magnetic fields in comparison with the as-synthesized sample and the magnitude of strain showed a maximum at approximately 0.2 T. Therefore, magnetostrictive properties of Cu_0.8Co_0.2Fe₂O₄ are strongly related to its crystal structure.

Zirconium-titanium (Zr-Ti) alloys are known for their superior strength, corrosion resistance, and biocompatibility, making them promising biomaterials. Among these, Zr-50Ti alloys exhibit a lower elastic modulus and reduced magnetic susceptibility compared to pure titanium (Ti), which diminishes stress shielding and minimizes interference during medical diagnostics. Despite these advantages, Zr-50Ti alloys lack inherent bioactivity, necessitating surface modification to enhance their ability to bond with bone. This study aimed to impart bioactivity to Zr-50Ti alloys through sulfuric acid treatment to create micropores, followed by treatment in a modified simulated body fluid (m-SBF) under moderate conditions (36.5 °C, pH 7.40). The bioactivity of the treated alloys was evaluated by soaking in simulated body fluid (SBF) for 1, 3, and 7 days. The results demonstrated that the sulfuric acid treatment significantly enhanced the calcium phosphate precipitation ability of Zr-50Ti alloys in m-SBF, leading to successful precipitation. This approach under mild conditions suggests the potential for further testing on materials suitable for biological conditions without additional restrictions.