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산업부산물 활용을 위한 고Al2O3 함량 OPC 클링커의 소성성 및 반응성에 관한 연구
강봉희,최재원,기태경,권상진,김규용 한국건설순환자원학회 2020 한국건설순환자원학회 논문집 Vol.8 No.3
This study evaluated the burnability and hydration reaction of clinker burned with high Al2O3 content OPC to apply large amounts of industrial by-products in the cement manufacturing process. Specifically, after preparing a clinker with a high C3A content by burning the OPC raw material with a high content of Al2O3 in a laboratory electric furnace, the burnability of the clinker was evaluated through XRD Rietveld analysis and polarization microscopy, and clinker hydration reactivity was reviewed through the Isothermal conduction calorimetry analysis and the cement compressive strength. As a result, the kiln burning temperature for the production of high Al2O3 content clinker lower, and the compressive strength was equal to or higher than OPC. Therefore it was confirmed the possibility to manufacturing energy-saving high Al2O3 content clinker using a large amount of industrial by-products.
박지민,김다은,김해빈,배중호,이예지,명재인,황은경,임태은,송준호,유지상,류지헌,Park, Ji Min,Kim, Daeun,Kim, Hae Bin,Bae, Joong Ho,Lee, Ye-Ji,Myoung, Jae In,Hwang, Eunkyoung,Yim, Taeeun,Song, Jun Ho,Yu, Ji-Sang,Ryu, Ji Heon 한국전기화학회 2016 한국전기화학회지 Vol.19 No.3
리튬이온 이차전지의 고용량화를 위해 high-Ni계 양극 활물질이 크게 주목받고 있으나, Ni 함량이 높아짐에 따라 고온 안정성이 감소하여 수명저하가 발생하게 된다. 본 연구에서는 $LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$ (NCM622)의 합성공정 중에서 전구체인 전이금속 수산화물과 리튬염의 열처리 과정에 알루미나 입자를 첨가함으로써 추가적인 표면처리 공정없이 활물질 특성을 개선시키고자 하였다. 알루미나를 첨가하게 되면 고온 사이클 수명이 개선되었으며, 특히 나노크기의 알루미나를 사용하는 경우에 초기용량의 감소도 적고 수명도 개선됨을 확인하였다. 그리고, 나노 알루미나를 함량별로 추가한 결과로 표면형상이 점차 변화함과 동시에 격자상수의 감소가 발생하는 것이 관찰되어 표면코팅과 구조 내 치환이 동시에 발생하고 있음을 확인하였다. LSTA (linear-sweep thermmametry)를 사용하여 알루미나의 함량이 증가할 수록 부반응이 감소하며 고온 안정성이 증가하는 것을 확인하였다. 또한 전이금속 대비 Al을 2.5 mol% 추가하는 경우에 가장 우수한 고온 사이클 성능이 나타나는 것을 확인하였다. High Ni content layered oxide materials for the positive electrode in lithium-ion batteries have high specific capacity. However, their poor electrochemical and thermal stability at elevated temperature restrict the practical use. A small amount of $Al_2O_3$ was added to the mixture of transition metal hydroxide and lithium hydroxide. The $LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$ was simultaneously doped and coated with $Al_2O_3$ during heat-treatment. Electrochemical characteristics of modified $LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$ were evaluated by the galvanostatic cycling and the LSTA(linear sweep thermmametry) at the constant voltage conditions. The nano-sized $Al_2O_3$ added materials show better cycle performance at elevated temperature than that of micro-sized $Al_2O_3$. As the added amount of nano-$Al_2O_3$ increased, the thermal stability of electrode also enhanced, but the use of 2.5 mol% Al showed the best high temperature performance.
Mechanical Properties of High Mg-Content Al-Mg-Sc-Zr Alloy Fabricated by Selective Laser Melting
Hao Tang,Yaoxiang Geng,Jinjie Luo,Junhua Xu,Hongbo Ju,Lihua Yu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8
The efects of process parameters and aging treatment on the microstructure and mechanical properties of selective lasermelting (SLM) fabricated high Mg-content Al-Mg-Sc-Zr aluminum alloy were systematically studied. Our experiment resultsshow that the samples exhibit good processability with porosity less than 1%. The increase of Mg content in Al-Mg-Sc-Zris benefcial to reduce the texture of the alloy. The laser scanning speed has a large infuence on the Vickers hardness ofas-fabricated samples. The maximum microhardness of as-fabricated sample reaches 148±2 HV with a compression yieldstrength of 342±7 MPa. After aging treatment, the distinction in microhardness of the samples obtained under diferent laserscanning speed is obviously reduced, and the mechanical properties of the samples are further improved with a maximummicrohardness of 175±5 HV and a maximum compressive yield strength of 476±10 MPa, which are superior to the knownAl-Mg-Sc-Zr alloy with same Sc and Zr content fabricated by SLM. In this study, a novel high Mg-content Al-Mg-Sc-Zraluminum alloy specifcally for SLM with good processability and mechanical properties was reported.
Al-고농도 Mg(≥7 wt.%) 합금의 β상 석출분해에 미치는 La 및 Mm 첨가의 효과
朴秀東,金秉杰 대한금속재료학회 2001 대한금속·재료학회지 Vol.39 No.12
In order to clarify the behavior of precipitation and dissolution in Al-Mg-(La, Mm) alloys with a high Mg content(x≥7 wt.%) in detail, the characteristic parameter of DVRC (Differentiated values of the ratio of electrical resistivity change) depending on temperature has been investigated at a slow heating rate (0.05 K/min). Since the value of DVRC is very sensitive to its microstructural change, it enables us to understand the precipitation and dissolution behavior of phases clearly and quantitatively. During the heating, the transformation process of precursor phase, such as G. P. zone, shown as a positive peak at low temperature region, was retarded and the precipitation of β phase was suppressed by La or Mm addition. And the homogeneous precipitation of β phase was also induced by the additive elements of La or Mm.
백창현,박용권,위명용,Park, Yong-Gwon,Park, Yong-Gwon,Wey, Myeong-Yong 한국재료학회 2002 한국재료학회지 Vol.12 No.8
Microstructure, mechanical properties, and oxidation resistance of TiAIN thin films deposited on quenched and tempered STD61 tool steel by arc ion plating were studied using XRD, XPS and micro-balance. The TiAIN film was grown with the (200) orientation. The grain size of TiAIN thin film decreased with increasing Al contents, while chemical binding energy increased with Al contents. When hard coating films were oxidized at $850^{\circ}C$ in air, oxidation resistance of both TiN and TiCN films became relatively lower since the surface of films formed non-protective film such as $TiO_2$. However, oxidation resistance of TiAIN film was excellent because its surface formed protective layer such as $_A12$$O_3$ and $_Al2$$Ti_{7}$$O_{15}$, which suppressed oxygen intrusion.
LiNi0.6Co0.2Mn0.2O2 양극 활물질의 합성공정 중나노크기 알루미나 추가에 의한 고온수명 개선
박지민,김다은,김해빈,배중호,이예지,명재인,황은경,임태은,송준호,유지상,류지헌 한국전기화학회 2016 한국전기화학회지 Vol.19 No.3
리튬이온 이차전지의 고용량화를 위해 high-Ni계 양극 활물질이 크게 주목받고 있으나, Ni 함량이 높아짐에 따라 고온 안정성이 감소하여 수명저하가 발생하게 된다. 본 연구에서는LiNi0.6Co0.2Mn0.2O2 (NCM622)의 합성공정 중에서 전구체인 전이금속 수산화물과 리튬염의 열처리 과정에 알루미나 입자를 첨가함으로써 추가적인 표면처리 공정없이 활물질 특성을 개선시키고자 하였다. 알루미나를 첨가하게 되면 고온 사이클 수명이 개선되었으며, 특히 나노크기의 알루미나를 사용하는 경우에 초기용량의 감소도 적고 수명도 개선됨을 확인하였다. 그리고, 나노 알루미나를 함량별로 추가한 결과로 표면형상이 점차 변화함과 동시에 격자상수의 감소가 발생하는것이 관찰되어 표면코팅과 구조 내 치환이 동시에 발생하고 있음을 확인하였다. LSTA (linearsweep thermmametry)를 사용하여 알루미나의 함량이 증가할 수록 부반응이 감소하며 고온 안정성이 증가하는 것을 확인하였다. 또한 전이금속 대비 Al을 2.5 mol% 추가하는 경우에 가장 우수한 고온 사이클 성능이 나타나는 것을 확인하였다.