Search Results (162)

With the expanding electric vehicle market, there is increasing demand for improved battery safety and fast-charging performance. Ceramic-based solid electrolytes have attracted attention due to their high thermal and electrochemical stabilities. Li-glass solid electrolytes (e.g., Li₂O–LiCl–B₂O₃–Al₂O₃, LCBA) are promising materials because they enable low-temperature sintering (<550 °C), suppress lithium volatilization, mitigate ionic conductivity degradation, and enable cost-effective manufacturing. LCBA can be co-sintered with graphite anodes to form composite anode materials for LCBA-based all-solid-state batteries. However, insufficient densification and shrinkage mismatch often lead to limited ionic conductivity and interfacial delamination. In this study, the sintering behavior of LCBA was investigated using a hot-press-assisted process, and LCBA/graphite composite anodes were co-sintered to evaluate their electrochemical and interfacial properties. The LCBA electrolyte sintered at 550 °C exhibited high densification and an ionic conductivity of 3.86 × 10⁻⁵ S cm⁻¹. Additionally, the composite containing 50 wt% LCBA achieved a maximum tensile stress of ~0.23 MPa and a high interfacial fracture energy of ~180–200 J m⁻², indicating enhanced deformation tolerance and fracture resistance. This approach improves the densification, ionic conductivity, and interfacial mechanical stability of LCBA solid electrolytes and their composite anodes, highlighting their potential for next-generation all-solid-state secondary battery applications. Full article

This study investigates the influence of different sintering protocols and resin cement shades on the optical properties of monolithic zirconia restorations. Zirconia, widely used in dentistry for its superior mechanical strength and esthetic potential, demonstrates phase transformations influenced by stabilizing oxides and processing conditions. While increasing yttria content enhances translucency, it compromises mechanical durability. Factors such as sintering temperature, grain size, porosity, and cement selection further affect translucency parameter, contrast ratio, and opalescence. In this research, 36 zirconia samples were divided into three groups according to sintering procedure performed; conventional, fast, and super-fast sintering. Each was tested with two shades of dual-cure resin cement (yellow and transparent). Optical parameters including translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) were measured using a spectrophotometer under controlled conditions. Statistically significant differences in OP values between the conventional sintering protocol and both the rapid and super-fast sintering protocols were found. A statistically significant difference was observed in OP values between the yellow and transparent cement groups. Neither the main effects of the sintering protocol nor the cement type were statistically significant on TP and CR values. However, a statistically significant interaction effect between the sintering protocol and cement type was observed for CR values. The findings highlight that both processing parameters and cement selection interaction play crucial roles in optimizing the TP and CR values of zirconia restorations, enabling improved esthetic outcomes in clinical practice. Full article

The solid joining between the WC-8Co cemented carbide and alloy steels has great significance for their extensive applications. In this study, the WC-8Co and 40Cr steel were joined with the Ag-28Cu interlayer through the SPS method. The microstructure and mechanical properties of the joints obtained at three temperatures—740 °C, 760 °C, and 780 °C—were analyzed. The joining mechanism was studied, and the relationship between the microstructure and shear strength of the joints was also revealed. When processed at 740 °C, the poor bonding between the interlayer and the 40Cr substrates damaged the joint strength. Higher bonding temperature helped to eliminate the interfacial defects. The joint bonded at 760 °C consists mainly of Ag, Cu within the interlayer and Co-rich Fe(s,s) at the substrate/interlayer interfaces, without any defects. In such a case, the shear strength of the joints reached the maximum level of 236 MPa. However, the increased residual stresses at higher bonding temperatures (780 °C) spoiled the strength of the joints, resulting in the decreasing of the shear strength to 173 MPa. The study shed light on the fast joining of the WC-Co and alloy steels at relatively low temperatures. Full article

This article presents the wear characteristics of the working surface of WC-Co (Tungsten Carbide–Cobalt) tungsten carbide tools obtained using the innovative U-FAST (Upgraded Field-Assisted Sintering Technology) method for particleboard machining. Three groups of tools with a similar chemical composition but differing WC (Tungsten Carbide) grain sizes were tested. Milling tests were carried out on a CNC (Computer Numerical Control) machine tool with the following cutting parameters: spindle rotation at 15,000 rpm, a feed rate of 0.25 mm per tooth, and a feed rate of 3.75. The experimental results show that tools with submicron WC grit sizes of 0.4 µm and 0.8 µm have the longest tool life. Wear of the cutting edges occurred through the removal of the cobalt bond between the tungsten carbide grains, leading to fracture and mechanical removal of the grains from the cutting edge surface. The similarities in the relative wear characteristics of blades with submicron tungsten carbide grain sizes suggest that micro-abrasion and bond phase extrusion may be the main wear mechanisms under the experimental conditions. Nanometric WC grain size significantly influences tool wear through chipping and cracking. Full article

In this study, a correlative approach using Raman spectroscopy and scanning electron microscopy (SEM) is introduced to meet the challenges of identifying impurities, especially carbon-related compounds in metal injection-molded (MIM) Mg-0.6Ca specimens designed for biomedical applications. This study addresses, for the first time, the issue of carbon residuals in the binder-based powder metallurgy (PM) processing of Mg-0.6Ca materials. A deeper understanding of the material microstructure is important to assess the microstructure homogeneity at submicron levels as this later affects material degradation and biocompatibility behavior. Both spectroscopic and microscopic techniques used in this study respond to the concerns of secondary phase distributions and their possible stoichiometry. Our micro-Raman measurements performed over a large area reveal Raman modes at ~1370 cm⁻¹ and ~1560 cm⁻¹, which are ascribed to the elemental carbon, and at ~1865 cm⁻¹, related to C≡C stretching modes. Our study found that these carbonaceous residuals/contaminations in the material microstructure originated from the polymeric binder components used in the MIM fabrication route, which then react with the base material components, including impurities, at elevated thermal debinding and sintering temperatures. Additionally, using evidence from the literature on thermal carbon cracking, the presence of both free carbon and calcium carbide phases is inferred in the sintered Mg-0.6Ca material in addition to the Mg₂Ca, oxide, and silicate phases. This first-of-its-kind correlative characterization approach for PM-processed Mg biomaterials is fast, non-destructive, and provides deeper knowledge on the formed residual carbonaceous phases. This is crucial in Mg alloy development strategies to ensure reproducible in vitro degradation and cell adhesion characteristics for the next generation of biocompatible magnesium materials. Full article

In this study, novel Al₆₀₆₁-(30-x)B₄C-xSm₂O₃ (x = 0, 1, 3, 5, 7, and 9 wt%) composites were fabricated using high-energy ball milling followed by cold pressing and sintering. The aim was to improve both the mechanical performance and radiation-shielding capabilities by integrating Sm₂O₃ as a reinforcement phase. Microstructural analyses via XRD and SEM-EDX revealed that the addition of Sm₂O₃ significantly enhanced phase uniformity, reduced porosity, and improved interfacial bonding, especially by mitigating the inherent poor wettability between Al₆₀₆₁ and B₄C. As a result, the relative density, hardness, and wear resistance were considerably improved with an increasing Sm₂O₃ content. Monte Carlo simulations (MCNP6.2) demonstrated that while thermal neutron shielding showed a slight decline due to the reduced boron content, fast neutron and gamma-ray attenuation were substantially enhanced owing to the high atomic number and density of Sm₂O_3. The results demonstrate that the mechanical performance and superior neutron-shielding properties contribute to new visions in material design and applications and have the potential to provide safer and more effective radiation-protection solutions that are environmentally sustainable. Full article

This in vitro study evaluated the impact of simulated gastric acid exposure on the optical (ΔE₀₀, translucency parameter TP, contrast ratio CR) and surface (roughness Ra) properties of monolithic zirconia ceramics under varying sintering rates and surface treatments. Forty-eight disc specimens (10 mm × 10 mm × 1.0 mm) were randomly allocated into four groups (n = 12): slow sintering + polishing; slow sintering + glazing; fast sintering + polishing; and fast sintering + glazing. Specimens were aged in 0.06 M of HCl (hydrochloric acid) for 96 h, and all measurement parameters were assessed against white and black backgrounds before and after aging. Statistical analyses (Shapiro–Wilk, Kruskal–Wallis, Wilcoxon tests; α = 0.05) revealed that acid aging caused a significant increase in ΔE₀₀ across all groups (p < 0.05), with the smallest change observed in the fast-sintering + glazing group and the largest in the slow-sintering + glazing group. Contrast ratios remained high in all groups (CR > 0.92), while only the slow-sintering + glazing group exhibited a significant reduction in TP (p < 0.05). Surface roughness decreased following aging in all groups, with the lowest Ra detected in the fast-sintering + glazing group. These results suggest that fast sintering combined with glazing enhances color stability and yields smoother surfaces under acidic conditions, recommending this protocol particularly for patients at elevated risk of increased oral acidity. Full article

Part defects in additive manufacturing (AM) operations like laser sintering (LS) can negatively affect the quality and integrity of the manufactured parts. Therefore, it is important to understand and mitigate these part defects to improve the performance and safety of the manufactured parts. Integrating machine learning to detect part defects in AM can enable efficient, fast, and automated real-time monitoring, reducing the need for labor-intensive manual inspections. In this work, a novel approach incorporating a lightweight Visual Geometry Group (VGG) structure with soft attention is presented to detect powder bed defects (such as cracks, powder bed ditches, etc.) in laser sintering processes. The model was evaluated on a publicly accessible dataset (called LS Powder bed defects) containing 8514 images of powder bed images pre-split into training, validation, and testing sets. The proposed methodology achieved an accuracy of 98.40%, a precision of 97.45%, a recall of 99.40%, and an f1-score of 98.42% with a computation complexity of 0.797 GMACs. Furthermore, the proposed method achieved better performance than the state-of-the-art in terms of accuracy, precision, recall, and f1-score on LS powder bed images, while requiring lower computational power for real-time application. Full article

Compared to traditional manufacturing methods, additive manufacturing (AM) enables the production of parts with arbitrary structures, effectively addressing the challenges faced when fabricating complex geometries using conventional techniques. The dynamic development of this technology has led to the emergence of increasingly advanced materials. One of the best examples is metal–polymer composites, which allow the manufacturing of fully dense components consisting of stainless steel and titanium alloys, employing the widely available AM technology based on material extrusion (MEX). Metallic materials intended for this type of 3D printing may serve as an alternative to currently prevalent techniques including techniques like selective laser melting (SLM), owing to significantly lower equipment and material costs. Particularly applicable in low-volume production, where total costs and manufacturing time are critical factors, MEX technology of polymer–metallic composites offer relatively fast and economical AM of metal components, proving beneficial during the design of geometrically complex, and low-cost equipment. Due to the significant advancements in AM technology, this review focuses on the latest developments in the additive manufacturing of metallic components using the MEX approach. The discussion encompasses the printing process characteristics, materials tailored to this technology, and post-processing steps (debinding and sintering) necessary for obtaining fully metallic MEX components. Additionally, the article characterizes the printing process parameters and their influence on the functional characteristics of the resulting components. Finally, it presents the drawbacks of the process, identifies gaps in existing research, and outlines challenges in refining the technology. Full article

Radar sensors are critical for obstacle detection and navigation, especially for automated driving. Using the use-case “printing of heating coils on the inside of the front housing (primary radome)” needed for de-icing in winter, it is demonstrated that additive manufacturing (AM) can provide economic and functional benefits for manufacturing of the sensors. AM will allow significant cost reduction by eliminating parts and simplifying the manufacturing process. Different AM technologies for the coils were investigated, first, by applying the conductive traces by fused deposition modeling (FDM), and, second, by printing copper particle-free inks and pastes. The metal layers were electrically and mechanically characterized using a profilometer to measure the trace dimension and a four-point probe to measure the resistance. It was revealed that low-cost conductive filaments with low resistivity and current carrying capacity are commercially still not available. The best option sourced was a copper–polyester-based filament with 6000 µΩcm after printing. Therefore, low-cost particle-free copper inks and commercial copper flake paste were selected to print the heating coil. The Cu particle-free inks were amine-based Cu (II) formate complexes, where the Cu exists in an ionic form. Using contactless printing processes such as ink-jet printing or pneumatic dispensing, the traces could be deposited onto the low-melting temperature (225 °C) polymeric radome structure. After printing, the material needed to be sintered to form the conductive copper traces. To avoid damaging the polymer radome during sintering, two different processes were investigated: low-temperature (<150 °C) sintering in an oven for 30 min or fast laser sintering. The sintered Cu layers achieved the following specific electric resistivities when slowly sintered in the oven: paste 4 µΩcm and ink 8.8 µΩcm. Using laser sintering, the ink achieved 3.2 µΩcm because the locally high temperature provides better sintering. Also, the adhesion was significantly increased to (5 B). Therefore, laser sintering is the preferred technology. In addition, it allows fast processing directly after printing. Commercial equipment is available where printing and laser sintering is integrated. The potential of low-cost copper material and the integration in additive manufacturing of electronic systems using radar sensors as an example are demonstrated in this paper. Full article

Background: Lamivudine is widely used alone or in combination with other anti-HIV drugs in the infant to adolescent age groups of pediatric populations. Compounding of medications is frequently used for pediatric patients. However, many issues have been reported for the compounded formulation such as assay, stability, safety, and efficacy. Three-dimensional printing can overcome these issues. Objective: The aim of this study was to understand the effect of process and formulation variables on lamivudine printlets for pediatric populations using selective laser sintering. Methods: The Plackett–Burman screening design was used to prepare 12 formulations to study six variables, namely, laser scanning speed (130–150 °C), surface temperature (105–120 °C), chamber temperature (250–350 mm/s), sucrose (0–30%), hydroxypropyl methylcellulose (0–42%), and Kollidon^® CL-M (0–5%). The formulations were tested for dissolution, disintegration, hardness, assay, X-ray diffraction, differential scanning calorimetry, stability, and pharmacokinetics in Sprague Dawley rats. Results: The assay of the printlet formulations varied between 93.1 and 103.5% and the disintegration time was 2.8 ± 1.2 (F1) to 43.7 ± 2.7 (F10) s. Due to high surface temperatures, the unsintered powder in the printing chamber experienced significant changes in crystallinity. No statistical significance was observed between the pharmacokinetic parameters of the printlets and commercial tablets (p > 0.05). The maximum plasma concentration (C_max), time to reach maximum plasma concentration (T_max), and area under the curve (AUC) of the printlets and commercial tablets were 295.5 ± 33.0 and 305.0 ± 70.1 ng/mL, 0.5 ± 0.0 and 1.0 ± 0.8 h, and 1414.1 ± 174.0 and 1987.2 ± 700.5 ng.h/mL, respectively. Conclusions: In summary, fast-disintegrating and dissolving 3D printed lamivudine was found to be bioequivalent to commercial formulation of lamivudine. Thus, it is a viable method for dispensing personalized lamivudine printlets for pediatric populations. Full article

Commercial NdFeB magnets are often coated with different thin layers to increase corrosion resistance. Fast and reliable test methods are being developed, especially for the automotive industry. Since corrosion test methods can inadequately describe the operating conditions of the e-motor, magnets are usually only tested in the demagnetized state. Corrosion tests close to sintered NdFeB magnet e-motor application conditions have been applied. Corrosion tests for sintered NdFeB magnets are usually demagnetized and performed in aqueous solutions or vapor environments instead of organic substances such as oil. In this study, sintered NdFeB magnets were immersed in a pre-saturated water-based salt solution and placed in gearbox oil. The test conditions have been specially selected to test the suitability of the magnets for e-motor applications (e.g., in hybrid vehicles). The microstructural effect of magnetic properties and corrosion resistance on the NdFeB magnets have been systematically studied. The aim of the study is the realization of the coating on the sintered NdFeB magnet, which provides high corrosion resistance and significantly reduces the thickness of the coating and ensures maximum efficiency in the use of magnets. The results of these studies are thought to play an important role in determining and optimizing the usage strategy of coated NdFeB magnets. Full article

Fused Deposition Modeling (FDM) is a prominent additive manufacturing technique known for its ability to provide cost-effective and fast printing solutions. FDM enables the production of computer-aided 3D designs as solid objects at macro scales with high-precision alignment while sacrificing excellent surface smoothness compared to other 3D printing techniques such as SLA (Stereolithography) and SLS (Selective Laser Sintering). Electro-Spinning (ES) is another technique for producing soft-structured nonwoven micro-scale materials, such as nanofibers. However, compared to the FDM technique, it has limited accuracy and sensitivity regarding high-precision alignment. The need for high-precision alignment of micro-scaled soft structures during the printing process raises the question of whether FDM and ES techniques can be combined. Today, the printing technique with such capability is called Melt Electro Writing (MEW), and in practice, it refers to the basic working principle on which bio-printers are based. This paper aims to examine how these two techniques can be combined affordably. Comparatively, it presents output production processes, design components, parameters, and materials used in output production. It discusses the limitations and advantages of such a hybrid platform, specifically from the perspective of engineering design and its biomedical applications. Full article

The basic material used for tools for machining wood and wood-based materials is WC-Co (Tungsten Carbide with Cobalt)-cemented carbide. The advantages of WC-Co carbides are significant resistance to high temperatures, high hardness, and wear resistance. Wood-based materials, such as particleboard, are particularly difficult to machine due to their considerable inhomogeneity and the presence of various types of hard particle inclusions, such as sand. In addition, unlike metals, wood has a low thermal conductivity, which means that most of the heat generated during milling is transferred to the tool. The consequence of this phenomenon is an increased tool temperature. In addition, the use of a coolant is not possible when machining wood-based materials. The durability of carbide blades is mainly influenced by grain size and cobalt content. When analysing WC-Co as a tool material, it is necessary to consider how it is obtained, as this can also significantly affect its properties. This paper presents the results of a durability study of cutting blades produced by the innovative Upgraded Field-Assisted Sintering Technology (U-FAST) sintering method during particleboard milling. The wear of the blades was measured until the wear value, i.e., the maximum loss at the contact surface VB_max, was 0.2 mm. Three groups of WC-Co carbides with different WC grain sizes were tested: 0.1, 0.4, and 0.8 µm. Three rotational speeds were used: 12,000, 15,000, and 18,000 rpm. In the machinability tests, blades with a WC grain size of 0.8 µm showed a twofold increase in tool life compared to commercial blades with a similar grain size gradation. Full article

Background/Objectives: Selective laser sintering (SLS) is one of the most promising 3D printing techniques for pharmaceutical applications as it offers numerous advantages, such as suitability to work with already approved pharmaceutical excipients, the elimination of solvents, and the ability to produce fast-dissolving, porous dosage forms with high drug loading. When the powder mixture is exposed to elevated temperatures during SLS printing, the active ingredients can be converted from the crystalline to the amorphous state, which can be used as a strategy to improve the dissolution rate and bioavailability of poorly soluble drugs. This study investigates the potential application of SLS 3D printing for the fabrication of tablets containing the poorly soluble drug carvedilol with the aim of improving the dissolution rate of the drug by forming an amorphous form through the printing process. Methods: Using SLS 3D printing, eight tablet formulations were produced using two different powder mixtures and four combinations of experimental conditions, followed by physicochemical characterization and dissolution testing. Results: Physicochemical characterization revealed that at least partial amorphization of carvedilol occurred during the printing process. Although variations in process parameters were minimal, higher temperatures in combination with lower laser speeds appeared to facilitate a greater degree of amorphization. Ultimately, the partial conversion to the amorphous form significantly improved the dissolution of carvedilol compared to its pure crystalline form. Conclusions: Obtained results suggest that the SLS 3D printing technique can be effectively used to convert poorly water-soluble drugs to their amorphous state, thereby improving solubility and bioavailability. Full article