간행물
한국재료학회지 KCI 등재 SCOPUS Korean Journal of Materials Research
- 발행기관 한국재료학회
- 자료유형 학술지
- 간기 월간
- ISSN 2799-8525 (Print)2799-8681 (Online)
- 수록기간 1991 ~ 2024
- 주제분류 공학 > 재료공학 공학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
제34권 제10호 (2024년 10월) 4건
1.
2024.10
구독 인증기관 무료, 개인회원 유료
3D printing using ceramic powder to produce precision ceramic parts has been studied with various additive manufacturing methods. This study analyzed problems occurring in alumina additive manufacturing that uses digital light processing (DLP) as well as methods to address such problems. For efficient analysis, we have classified alumina additive manufacturing into three types according to the driving method of the build platform - lifting type (LT), tilting type (TT) of the vat, and blade movement type (BT). LT had a problem with detachment and cracking of the alumina green body. However, this could be prevented by carefully controlling the cure depth of the suspension slurry and the bonding force between layers and improving the material used for coating the vat. TT, which resulted in non-uniform alumina additive manufacturing, could be improved by modifying the bidirectionality of the axis and the fluidity of the highly viscous alumina suspension slurry. BT resulted in detachment of the specimen as well as non-uniform results, but this could be avoided by shortening the shifting distance of the alumina suspension when it is introduced to the build platform, and enabling effective spreading.
4,000원
2.
2024.10
구독 인증기관 무료, 개인회원 유료
Nobuhiko Azuma, Hiroki Sawada, Hirotaka Ito, Ryosuke Sakagami, Yuya Tanaka, Tatsuhide Fujioka, Masanori Matoba, Yoichi Kamihara
Electrical and thermal transport properties of a polycrystalline carrier-doped wide-gap semiconductor LaCu1-δ S0.5Se0.5O (δ = 0.01), in which the CuCh (Ch = S, Se) layer works as conducting layer, were measured at temperatures 473~673 K. The presence of δ = 0.01 copper defects dramatically reduces the electrical resistivity (ρ) to approximately one part per million compared to that of δ = 0 at room temperature. The polycrystalline δ = 0.01 sample exhibited ρ of 1.3 × 10-3 Ωm, thermal conductivity of 6.0 Wm-1 K-1, and Seebeck coefficient (S) of 87 μVK-1 at 673 K. The maximum value of the dimensionless figure of merit (ZT) of the δ = 0.01 sample was calculated to be 6.4 × 10-4 at T = 673 K. The ZT value is far smaller than a ZT ~ 0.01 measured for a nominal LaCuSeO sample. The smaller ZT is mainly due to the small S measured for LaCu1-δS0.5Se0.5O (δ = 0.01). According to the Debye model, above 300 K phonon thermal conductivity in a pure lattice is inversely proportional to T, while thermal conductivity of the δ = 0.01 sample increases with increasing T.
4,200원
3.
2024.10
구독 인증기관 무료, 개인회원 유료
Lithium-ion batteries are widely used in various advanced devices, including electric vehicles and energy storage devices. As the application range of lithium-ion batteries expands, it will be increasingly important to improve their gravimetric and volumetric energy density. Layer-structured oxide materials have been widely adopted as cathode materials in Li-ion batteries. Among them, LiNiO2 has attracted interest because of its high theoretical capacity, ~274 mAh g-1, assuming reversible one Li+-(de)intercalation from the structure. Presently, such layered structure cathode materials are prepared by calcination of precursors. The precursors are typically hydroxides synthesized by coprecipitation reaction. Precursors synthesized by coprecipitation reaction have a spherical morphology with a size larger than 10 μm. Spherical precursors in the several micrometer range are difficult to obtain due to the limited coprecipitation reaction time, and can lead to vigorous collisions between the precursor particles. In this study, spherical and small-sized Ni(OH)2 precursors were synthesized using a new synthesis method instead of the conventional precipitation method. The highest capacity, 170 mAh g-1, could be achieved in the temperature range of 730~760 °C. The improved capacity was confirmed to be due to the higher quality of the layered structure.
4,000원
4.
2024.10
구독 인증기관 무료, 개인회원 유료
In this study, ferric phosphate precursors were prepared by controlling precipitation time, and the resulting LiFe PO4 active materials were thoroughly investigated. Microscale LiFePO4 cathode materials, designed for high energy density at the cell level, were successfully synthesized through a 10 h co-precipitation. As the reaction time increased, smaller primary particles were aggregated more tightly, and the secondary particles exhibited a more spherical shape. Meanwhile, ammonia did not work effectively as a complexing agent. The carbon coated LiFePO4 (LiFePO4/C) synthesized from the 10 h ferric phosphate precursor exhibited larger primary and secondary particle sizes, a lower specific surface area, and higher crystallinity due to the sintering of the primary particles. Enhanced battery performance was achieved with the LiFePO4/C that was synthesized from the precursor with the smaller size, which exhibited the discharge capacity of 132.25 mAh ‧ g-1 at 0.1 C, 70 % capacity retention at 5 C compared with 0.1 C, and 99.9 % capacity retention after the 50th cycle. The better battery performance is attributed to the lower charge transfer resistance and higher ionic conductivity, resulting from smaller primary particle sizes and a shorter Li+ diffusion path.
4,000원
