• Proceedings of the Korean Magnestics Society Conference
• /
• 2003.12a
• /
• pp.334-334
• /
• 2003

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.04a
• /
• pp.192.1-192
• /
• 2003

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.103.2-103
• /
• 2003

• Journal of the Korean Electrochemical Society
• /
• v.7 no.1
• /
• pp.1-8
• /
• 2004

This paper deals with the recent development of high-voltage cathode materials of mono- and di- metal ions substituted spinel $LiMn_2O_4$ for lithium batteries. $LiCu_xMn_{2-x}O_4(0{\leq}x{\leq}0.5)$ shows reversible intercalation/deintercalation in two potential regions, $3.9\~43\;and\;4.8-5.0V$ and stable electrochemical cycling behavior but with low capacity. $LiNi_{0.5}Mn_{1.5}O_4$ obtained by a sol-gel process delivers a capacity of 127mAh $g^{-1}$ on the first cycle and sustains a value of 124 mAh $g^{-1}$ even after the 60th cycle. The $Li_xCr_yMn_{2-y}O_4(0{\leq}x{\leq}0.5)$ solid-solutions exhibit enhanced specific capacity, larger average voltage, and improved cycling behaviors for low Cr content. $LiCr_yMn_{2-y}O_4$ presents a reversible Li deintercalation process at 4.9V, whose capacity is proportional to the Cr content in the range of $0.25{\leq}x{\leq}0.5$ and delivers higher capacities. $LiM_yCr_{0.5-y}Mn_{1.5}O_4(M=Fe\;or\;Al)$ shows that the capacity retention is lowered compared with lithium manganate. The cumulative capacities obtainable with Al-substitutted materials are less than those with Fe-substituted materials. $LiCr_xNi_{0.5-x}Mn_{1.5}O_4(x=0.1)$ delivers a high initial capacity of 1$152mAh\;g^{-1}$ with excellent cycleability.

• Corrosion Science and Technology
• /
• v.11 no.1
• /
• pp.9-14
• /
• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.8
• /
• pp.2379-2382
• /
• 2010

• Journal of electromagnetic engineering and science
• /
• v.5 no.4
• /
• pp.161-165
• /
• 2005

We prepared Mn-Zn ferrite Electromagnetic(EM) wave absorbers. The Mn-Zn ferrite EM wave absorbers were coated with Sr ferrite powders and $Al(OH)_3$ powders. The coated Mn-Zn ferrite EM wave absorbers show improved absorption compared with non-coated Mn-Zn EM wave absorbers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.05a
• /
• pp.133-137
• /
• 1994

Infrared radiator of Cordierite system were manufactured using Cordierite(2Mgo$.$2Al$_2$O$_3$$.$5SiO$_2$) and Clay 30wt% as main materials and addition of MnO$_2$ from 0. 1 to 2 5wt% of Dry pressing and slip casting The effects of MnO$_2$ additives on the thermal properties of infrared radiator of Cordierite system. The more the thermal expansion could be lowered the more the amount (wt%) of additives MnO$_2$is increased in the below 4.5$\mu\textrm{m}$. The high efficiency Infrared radiator of Cordierite system using dry pressing method when the amount of additives MnO$_2$is 2.0 wt%

• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
• /
• pp.584-584
• /
• 2000

Electronic structures of ordered Fe$_3X (X = Al, Si), and their derivative ternary alloys of Fe_2TX (T = 3d transition metal) have been investigated by using the linearized muffin-tin orbital (LMTO) band method. The role of the coupling between substituted transition metal and its neighbors is investigated by calculating the magnetic moments and local density of states (LDOS). It is shown that it is essential to include the coupling beyond nearest neighbors in obtaining the magnetic moment of Fe alloy. The preferential sites of T impurities in Fe_3X are determined from the total energy calculations. The derivative ternary alloys of Fe_2TX have characteristic electronic structures of semi-metal for Fe_2VAI and (nearly) half-metal for Fe_2TAI (T = Cr, Mn) and Fe_2TSi (T = V, Cr, Mn)

• Journal of the Korean Society of Groundwater Environment
• /
• v.4 no.3
• /
• pp.116-121
• /
• 1997

Pilot wetland reactor systems to test acid mine drainage treatment efficiencies for metals were designed and operated at the Dalsung mine and surveyed the operating problems. pH and Eh (redox potential) were measured in situ and anayses of Cd, Pb, As, Zn, Cu, Fe, Al and Mn were carried out in the laboratory. Maximum metal removal efficiencies of the reactor containing the rice stalks, the cow manure and limestones were that Cu, Zn, Fe, Cd, Al, Mn and Pb were lowered by 98%, 100%, 99%, 100%, 97%, 61% and 100%, respectively and at that time the pH and Eh of the effluents from the reactor were 6 and about -300 mV. However, the redox potential was raised and removal of metal elements except aluminium was decreased with operation time. It suggests that the reduced condition is very important for the metal removal. During the operation, problems such as scaling in pipes and volume change of the substrate within the reactor occurred, which were preventing the flow of main drainage in pipes and reactor.