Additive manufacturing makes it possible to improve the mechanical properties of alloys through segregation engineering of specific alloying elements into the dislocation cell structure. In this study, we investigated the mechanical and microstructural characteristics of CoNi-based medium-entropy alloys (MEAs), including the refractory alloying element Mo with a large atomic radius, manufactured via laser-powder bed fusion (L-PBF). In an analysis of the printability depending on the processing parameters, we achieved a high compressive yield strength up to 653 MPa in L-PBF for (CoNi)85Mo15 MEAs. However, severe residual stress remained at high-angle grain boundaries, and a brittle μ phase was precipitated at Mo-segregated dislocation cells. These resulted in hot-cracking behaviors in (CoNi)85Mo15 MEAs during L-PBF. These findings highlight the need for further research to adjust the Mo content and processing techniques to mitigate cracking behaviors in L-PBF-manufactured (CoNi)85Mo15 MEAs.

High-entropy alloys (HEAs) represent a revolutionary class of materials characterized by their multi-principal element compositions and exceptional mechanical properties. Powder metallurgy, a versatile and cost-effective manufacturing process, offers significant advantages for the development of HEAs, including precise control over their composition, microstructure, and mechanical properties. This review explores innovative approaches integrating powder metallurgy techniques in the synthesis and optimization of HEAs. Key advances in powder production, sintering methods, and additive manufacturing are examined, highlighting their roles in improving the performance, advancement, and applicability of HEAs. The review also discusses the mechanical properties, potential industrial applications, and future trends in the field, providing a comprehensive overview of the current state and future prospects of HEA development using powder metallurgy.

Ceramic materials have become essential due to their high durability, chemical stability, and excellent thermal stability in various advanced industries such as aerospace, automotive, and semiconductor. However, high-performance ceramic materials face limitations in commercialization due to the high cost of raw materials and complex manufacturing processes. Aluminum borate (Al₁₈B₄O₃₃) has emerged as a promising alternative due to its superior mechanical strength and thermal stability, despite its simple manufacturing process and low production cost. In this study, we propose a method for producing Al₁₈B₄O₃₃ spherical powder with increased uniformity and high flowability by controlling the particle size of B₂O₃. The content ratio of the manufactured Al18B4O33 spherical powder was Al2O3: B2O3 = 87:13, and it exhibited a 17% reduction in the Hausner ratio (1.04) and a 29% decrease in the angle of repose (23.9°) compared to pre-milling conditions, demonstrating excellent flowability.

The study examined the impact of adding acorn pomace dried powder (APDP) at different levels (0%, 5%, 10%, 15%, 20% w/w) on the quality, antioxidant potential, and consumer preference of garaetteok, a Korean rice cake. The findings showed that as the APDP content increased, moisture levels decreased, and pH levels were affected. Color analysis revealed a decrease in lightness (L), while yellowness (b) and redness (a) values increased. Texture analysis indicated an increase in gumminess, hardness, and chewiness, but a decrease in cohesiveness, adhesiveness, and springiness with higher APDP levels. Sensory evaluation of appearance, taste, flavor, texture, and overall preference identified the sample with 10% APDP as the most preferred. Additionally, the antioxidant activity of the garaetteok demonstrated a positive correlation with the increasing APDP content. In conclusion, the incorporation of 10% APDP enhanced the quality characteristics of garaetteok, improving its nutritional value, antioxidant properties, and overall consumer appeal.

This review examines the microstructural and mechanical properties of a Ti-6Al-4V alloy produced by wrought processing and powder metallurgy (PM), specifically laser powder bed fusion (LPBF) and hot isostatic pressing. Wrought methods, such as forging and rolling, create equiaxed alpha (α) and beta (β) grain structures with balanced properties, which are ideal for fatigue resistance. In contrast, PM methods, particularly LPBF, often yield a martensitic α′ structure with high microhardness, enabling complex geometries but requiring post-processing to improve its properties and reduce stress. The study evaluated the effects of processing parameters on grain size, phase distribution, and material characteristics, guiding the choice of fabrication techniques for optimizing Ti-6Al-4V performance in aerospace, biomedical, and automotive applications. The analysis emphasizes tailored processing to meet advanced engineering demands.

This study investigated the optimal process conditions and mechanical properties of Cu-10Sn alloys produced by the powder bed fusion (PBF) method. The optimal PBF conditions were explored by producing samples with various laser scanning speeds and laser power. It was found that under optimized conditions, samples with a density close to the theoretical density could be fabricated using PBF without any serious defects. The microstructure and mechanical properties of samples produced under optimized conditions were investigated and compared with a commercial alloy produced by the conventional method. The hardness, maximum tensile strength, and elongation of the samples were significantly higher than those of the commercially available cast alloy with the same chemical composition. Based on these results, it is expected to be possible to use the PBF technique to manufacture Cu-10Sn products with complex 3D shapes that could not be made using the conventional manufacturing method.

2022년 기준 국내 폐타이어 발생량은 약 37만톤으로 그 중 88.9% 인 약 32만 9천톤이 재활용되는 것으로 조사되었다. 하지만 이 중 약 75%가 시멘트소성로용 등 열이용 분야에 사용되었다. 폐타이어는 대부분 고무와 플라스틱으로 이루어져 있기 때문에, 고온에서 분 해되면서 다양한 유해가스와 오염물질이 발생할 수 있고, 이러한 공해물질은 적극적으로 관리되지 않으면 대기오염, 수질 오염 등 다 양한 환경문제를 발생시킬 수 있다. 때문에 친환경적이고 지속적인 재활용에 대한 필요성이 대두되고 있다. 폐타이어 고무 분말을 아스팔트 혼합물의 골재 일부로 치환하여 재활용하는 접근 방식은 환경에 미치는 영향을 완화할 뿐만 아니라 천연 자원의 고갈 측면에서도 긍정적인 영향을 미치는 것으로 판단된다. 따라서 타이어분말을 아스팔트 혼합물에 적용하는 것은 환경 문제를 해결하고 자원 효율성을 높이는 두 가지 이점을 가지고 있다. 폐타이어 분말을 아스팔트 바인더와 아스팔트 혼합물에 적용할 경우 미치는 영향을 평가하기 위하여 TTI의 반사균열 저항성 시험, FN Test를 진행하였다.

Molybdenum, valued for its high melting point and exceptional physical and chemical properties, is studied in diverse fields such as electronics, petrochemicals, and aviation. Among molybdenum oxides, molybdenum dioxide stands out for its higher electrical conductivity than other transition metal oxides due to its structural characteristics, exhibiting metallic properties. It is applied as pellets to gas sensors, semiconductors, and secondary batteries for its properties. Thus, research on molybdenum dioxide compaction and pressureless sintering is necessary, yet research on pressureless sintering is currently insufficient. This study synthesized MoO₃ powder via solution combustion synthesis and reduced it using the 3% hydrogen/argon gas mixture to investigate the effect of reduction temperature on the powder. Additionally, the reduced powder was compacted and subjected to pressureless sintering with temperature as a variable. The density and the microstructure of brown parts were analyzed and discussed.

This study analyzed the influence of ball size and process control agents on the refinement and dehydrogenation behavior of TiH2 powder. Powders milled using ZrO2 balls with diameters of 0.1 mm, 0.3 mm, and 0.3+0.5+1 mm exhibited a bimodal particle size distribution, of which the first mode had the smallest size of 0.23 μm for the 0.3 mm balls. Using ethanol and/or stearic acid as process control agents was effective in particle refinement. Thermogravimetric analysis showed that dehydrogenation of the milled powder started at a relatively low temperature compared to the raw powder, which is interpreted to have resulted from a decrease in particle size and an increase in defects. The dehydrogenation kinetics of the TiH2 powder were evaluated by the magnitude of peak shift with heating rates using thermogravimetric analysis. The activation energy of the dehydrogenation reaction, calculated from the slope of the Kissinger plot, was measured to be 228.6 kJ/mol for the raw powder and 194.5 kJ/mol for the milled powder. TEM analysis revealed that both the milled and dehydrogenated powders showed an angular shape with a size of about 200 nm.

In this study, chicken fry was made using batter prepared from a frying pre-mix that replaced wheat flour (WF) with floury rice powder (FRP) at ratios of 0% (control group), 25% (FRP-25 group), 50% (FRP-50 group), 75% (FRP-75 group), and 100% (FRP-100 group). The physicochemical and acceptability of the finished chicken fry were assessed to provide basic data for product development studies using FRP. The experimental groups that replaced WF with FRP showed higher water binding capacity and lower fat binding capacity than the control group (p<0.05). The viscosity of the batter decreased significantly as the proportion of FRP increased (p<0.05). The pick-up rate measurement results showed significantly lower values in experimental groups compared to the control group (p<0.05). The color measurement results of the chicken fry showed that as the substitution ratio of FRP to WF increased, lightness decreased, and redness increased (p<0.05). The browning index also showed a significant increase as the substitution ratio of FRP increased. The acceptance test results showed that the FRP-100 experimental group was significantly higher in all acceptability characteristics than the control group (p<0.05).

This study was conducted to present primary data for the development of functional beverages by measuring quality characteristics and antioxidant properties and preparing coffee with dried fruit powder. The pH, water content, and brownness were higher in the control group than in the fruit-added sample group. Total polyphenols were highest in the Prunus Fruit Coffee (PFC) at 2765.43±87.03 mg GAE/L. In terms of DPPH, the fruit addition group (consisting of dried apple, dried cherry, and dried plum) was higher than the control group, and the LFC was the highest at 70.04±2.01%. ABTS showed high antioxidant properties in all sample groups, and LFC showed the highest content at 83.01±1.06%. Caffeine was the highest in the control group, all sample groups showed lower content than the control group, and AFC showed the lowest content at 664.70±16.36. As a result, the fruit-added coffee groups are higher than the control groups in terms of quality characteristics and antioxidant properties, and it is considered that the fruit groups are suitable as functional food materials when developing coffee products.

In this study, chemical properties and functional ingredients of ginger and ginger pomace discarded after juice were analyzed. Ginger and ginger pomace were subjected to hot air drying, steaming, followed by hot air drying, soaking in vitamin C for 1 hour and 3 hours. When soaked in vitamin C for 3 hours, the moisture content was highest at 9.2% for ginger and 7.3% for ginger pomace. Among inorganic ingredients, the potassium (K) content was high at 2,633.6 mg% in hot air-dried ginger after steaming and at 1,584.3 mg% in ginger pomace. Total flavonoid content of ginger pomace was high at 67.3 mg/g when soaked in vitamin C for 3 hours. Gingerol content was the highest at 9.8 mg/g when ginger was dried with hot air. It was 10.5 mg/g in ginger pomace. After ginger pomace was steamed and dried with hot air, shogaol content was as high as 2.0 mg/g.

Sprout products, such as broccoli, alfalfa, and cabbage, have positive health effects. Thus far, sprout foods have attracted attention owing to their good bioavailability. In particular, young broccoli sprouts exhibit anti-inflammatory, antioxidant, and anti-cancer effects. They contain 100 times more chemoprotective substances than adult broccoli. This study examined the anti-inflammatory effects of freeze-dried young sprout broccoli (FD-YB) in vitro using RAW264.7 macrophage cells. The FDYB powder antioxidant ability test showed that the radical-scavenging activity and superoxide dismutase enzyme activity increased in a dose-dependent manner. In addition, FD-YB was not cytotoxic to RAW264.7 cells, and nitric oxide production decreased after the FD-YB treatment of lipopolysaccharide-stimulated RAW264.7 cells in a dose-dependent manner. Furthermore, FD-YB significantly decreased the expression of inflammation-related proteins (Cyclooxygenase-2, Inducible nitric oxide synthase, and Prostaglandin E Synthase 2) and cytokines (Tumor necrosis factor- and Interleukin-6). In conclusion, FD-YB can be a potential nutraceutical for preventing and regulating excessive immune responses during inflammation.

This study investigated the influence of incorporating chestnut inner shell powder (CISP) at varying levels (0%, 3%, 6%, 9%, and 12% w/w) on the quality, antioxidant potential, and consumer preference of garaetteok, a Korean rice cake. Findings revealed a decrease in moisture content and pH with increasing CISP content. Color analysis indicated a reduction in lightness (L) and yellowness (b) values, while redness (a) values increased. Textural properties displayed an increase in hardness, chewiness, and gumminess, but a decrease in springiness, adhesiveness, and cohesiveness with increasing CISP levels. Sensory evaluation for appearance, taste, flavor, texture, and overall preference revealed the sample containing 6% CISP to be the most favorable. Moreover, the antioxidant activity of the garaetteok exhibited a positive correlation with increasing CISP content. In conclusion, incorporating 6% CISP resulted in improved quality characteristics for garaetteok development, offering enhanced nutritional value, antioxidant properties, and overall consumer preference.

In this study, in order to develop an foaming tablet product using yuzu powder, yuzu powder was manufactured using different drying methods such as freeze-drying, 60℃ drying, and 40℃ drying, and then quality characteristics and functionality were analyzed. The naringin content per g of yuzu powder was 8.9 mg for freeze-drying and 8.8 mg for 60℃ drying, and the hesperidin content per g of yuzu powder was highest at 53.6 mg for freeze-drying and 46.2 mg for 60℃ drying. followed by 40℃ drying (41.7 mg). The tyrosinase inhibitory activity of 60℃ dried powder was found to be twice as high as that of freeze dried powder. Accordingly, in order to develop an inner beauty product, foaming tablets were manufactured using hot air dried powder, and the quality characteristics and functional ingredients of the final foaming tablets were investigated. The foaming tablet prepared with yuzu powder content of 10 and 15% showed an inhibitory activity of tyrosinase of 73.7 %, which was 1.6 times higher than that of ascorbic acid (1 mM), which was a positive control, confirming its melanin production inhibition effect.

In order to predict the process window of laser powder bed fusion (LPBF) for printing metallic components, the calculation of volumetric energy density (VED) has been widely calculated for controlling process parameters. However, because it is assumed that the process parameters contribute equally to heat input, the VED still has limitation for predicting the process window of LPBF-processed materials. In this study, an explainable machine learning (xML) approach was adopted to predict and understand the contribution of each process parameter to defect evolution in Ti alloys in the LPBF process. Various ML models were trained, and the Shapley additive explanation method was adopted to quantify the importance of each process parameter. This study can offer effective guidelines for fine-tuning process parameters to fabricate high-quality products using LPBF.

Because collagen is inherently piezoelectric, research is being actively conducted to utilize it to harvest energy. In this study, a collagen solution was prepared using edible low-molecular-weight peptide collagen powder, and collagen films were fabricated using a dip coating method. The collagen films prepared by dip coating showed a smooth surface without defects such as pinholes or cracks. Dehydrothermal treatment of the collagen films was performed to induce a stable molecular structure through cross-linking. The collagen film subjected to dehydrothermal treatment at 110 °C for 24 h showed a thickness reduction rate of 19 %. Analysis of the collagen films showed that the crystallinity of the collagen film improved by about 7.9 % after dehydrothermal treatment. A collagen film-based piezoelectric nanogenerator showed output characteristics of approximately 13.7 V and 1.4 μA in a pressure test of 120 N. The generator showed a maximum power density of about 2.91 mW/m2 and an output voltage of about 8~19 V during various human body movements such as finger tapping. The collagen film-based piezoelectric generator showed improved output performance with improved crystallinity and piezoelectricity after dehydrothermal treatment.

This study investigated the effects of revolution speed and ball size in planetary milling on the microstructure and dehydrogenation behavior of TiH2 powder. The particle size analysis showed that the large particles present in the raw powder were effectively refined as the revolution speed increased, and when milled at 500 rpm, the median particle size was 1.47 μm. Milling with a mixture of balls of two or three sizes was more effective in refining the raw powder than milling with balls of a single size. A mixture of 3 mm and 5 mm diameter balls was the optimal condition for particle refinement, and the measured median particle size was 0.71 μm. The dependence of particle size on revolution speed and ball size was explained by changes in input energy and the number of contact points of the balls. In the milled powder, the endothermic peak measured using differential thermal analysis was observed at a relatively low temperature. This finding was interpreted as the activation of a dehydrogenation reaction, mainly due to the increase in the specific surface area and the concentration of lattice defects.