• 한국분말재료학회지
• /
• 제20권5호
• /
• pp.359-365
• /
• 2013

In this study, we fabricated $Nd_2Fe_{14}B$ hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of $Nd_2Fe_{14}B$. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentrations of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to control the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of $Nd_2Fe_{14}B$ phase and magnetic properties was investigated.

• 한국세라믹학회지
• /
• 제39권11호
• /
• pp.1017-1022
• /
• 2002

$(Ba_{1-x}Ca_x)(Ti_{1-y}Zr_y)O_3(BCTZ)$ powders for the Ni-electrode Multilayer Ceramic Capacitor(MLCC) were synthesized via hydrothermal treatment using mixed aqueous solutions of $BaCl_2{\cdot}2H_2O,\Ca(NO_3)2{\cdot}4H_2O,\ ZrOCl_2{\cdot}8H_2O$ and $TiCl_4$. Two component and three component systems were also extensively studied for basic data. BT, CT and BZ powders were crystalline but CZ was determined to be amorphous under the same synthetic condition. In BTZ system, Zr and Ti were completely soluble and Ca would be substituted for Ba up to ∼6 mol% in BCT. The submicron-sized $(Ba_{0.95}Ca_{0.05})(Ti_{0.80}Zr_{0.20})O_3$ powder of the target composition was successfully synthesized at $150{\circ}$ for 12h.

• 한국분말재료학회지
• /
• 제18권3호
• /
• pp.256-261
• /
• 2011

In order to make a $Cu_2ZnSnSe_4$ (CZTSe) sputtering target sintered for solar cell application, synthesis of CZTSe compound by solid state reaction of Cu, Zn, Sn and Se mixed powders and effects of ball milling condition on sinterability such as ball size, combination of ball size, ball milling time and sintering temperature, was investigated. As a result of this research, sintering at $500^{\circ}C$ after ball milling using mixed balls of 1 mm and 3 mm for 72 hours was the optimum condition to synthesis near stoichiometric composition of $Cu_2ZnSnSe_4$ and to prepare sintered pellet with high density relatively.

• 한국전기전자재료학회논문지
• /
• 제29권10호
• /
• pp.665-670
• /
• 2016

Prevailing dissemination of machine tools and cutting technology have caused drastic developments of high speed dry machining with work materials of high hardness, and demands on the high-hardness-materials with high efficiency have become increasingly important in terms of productivity, cost reduction, as well as environment-friendly issue. Addition of Si to TiAlN has been known to form nano-composite coating with higher hardness of over 30 GPa and oxidation temperature over $1,000^{\circ}C$. However, it is not easy to add Si to TiAlN by using conventional PVD technologies. Therefore, Ti-Al-Si-N have been prepared by hybrid process of PVD with multiple target sources or PVD combined with PECVD of Si source gas. In this study, a single composite target of Ti-Al-Si was prepared by powder metallurgy of MA (mechanical alloying) and SPS (spark plasma sintering). Properties of he resulting alloying targets were examined. They revealed a microstructure with micro-sized grain of about $1{\sim}5{\mu}m$, and all the elements were distributed homogeneously in the alloying target. Hardness of the Ti-Al-Si-N target was about 1,127 Hv. Thin films of Ti-Al-Si-N were prepared by unbalanced magnetron sputtering method by using the home-made Ti-Al-Si alloying target. Composition of the resulting thin film of Ti-Al-Si-N was almost the same with that of the target. The thin film of Ti-Al-Si-N showed a hardness of 35 GPa and friction coefficient of 0.66.

• 한국분말재료학회지
• /
• 제21권5호
• /
• pp.349-354
• /
• 2014

This study is a basic research for repair material production which manufactured a Cu repair coating layer on the base material of a Cu plate using kinetic spray process. Furthermore, the manufactured material underwent an annealing heat treatment, and the changes of microstructure and macroscopic properties in the Cu repair coating layer and base material were examined. The powder feedstocks were sphere-shaped pure Cu powders with an average size of $27.7{\mu}m$. The produced repair coating material featured $600{\mu}m$ thickness and 0.8% porosity, and it had an identical ${\alpha}$-Cu single phase as the early powder. The produced Cu repair coating material and base material displayed extremely high adhesion characteristics that produced a boundary difficult to identify. Composition analysis confirmed that the impurities in the base material and repair coating material had no significant differences. Microstructure observation after a $500^{\circ}C/1hr$. heat treatment (vacuum condition) identified recovery, recrystallization and grain growth in the repair coating material and featured a more homogeneous microstructure. The hardness difference (${\Delta}H_v$) between the repair coating material and base material significantly reduced from 87 to 34 after undergoing heat treatment.

• 한국수소및신에너지학회논문집
• /
• 제35권3호
• /
• pp.336-344
• /
• 2024

In this study, a Ni_0.9Co_0.05Mn_0.05(OH)₂ precursor used as an anode active material using a black powder leaching solution of a recycled lithium ion battery was prepared through coprecipitation synthesis with co-precipitation time, NH₄OH concentration, pH, and stirring time as variables. The characteristics of the prepared powder were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), particle size analysis (PSA), and inductively coupled plasma optical emission spectroscopy (ICP-OES). It was confirmed that the single crystal thickness of the LiNi_1-x-yCo_xMn_yO₂ (NCM) precursor changes depending on the NH₄OH concentration and reaction pH value, and thicker single crystals are formed at 2 M NH₄OH compared to 1 M and at pH 10.8-11.8 compared to pH 11.8-12.0. NCM precursor particles increased with coprecipitation time, and it was confirmed that the 72 hours NCM precursor had the largest particle size. Through ICP-OES analysis, it was confirmed that the NCM precursor was synthesized with the target composition of Ni²⁺:Co²⁺:Mn²⁺=90:5:5.

• 공업화학
• /
• 제21권2호
• /
• pp.224-229
• /
• 2010

Transparent conducting oxide (TCO) 박막은 평판 디스플레이 산업에 널리 사용되고 있다. 화학적으로 우수한 투명전도성 Indium Zinc Oxide (IZO) 필름은 Indium Tin Oxide (ITO) 필름의 대체 물질로 관심을 끌고 있다. 본 연구에서는 90 : 10 wt%의 $In_2O_3$와 ZnO를 혼합하여 만든 타겟으로 전자빔 증착법을 이용하여 polynorbornene (PNB) 기판 위에 IZO 박막을 제조하였다. UV/Visible spectrophotometer, 4-Point Probe를 이용하여 증착 두께와 산소도입 속도에 따른 IZO 필름의 전기적 및 광학적 특성을 연구하였으며, SEM, XRD 및 XPS를 이용하여 증착된 IZO의 구조적 특성 및 표면조성비를 연구하였다.

• 한국표면공학회지
• /
• 제35권1호
• /
• pp.39-46
• /
• 2002

$Cu_2$$ZnSnS_4$(CZTS) thin film is one of the candidate materials for the solar cell. It has an excellent optical absorption coefficient as well as appropriate 1.4~1.5eV band gap. The purpose of this study is replacing a half of high-cost Indium(In) atoms with low-cost Zinc(Zn) atoms and the other half with low-cost Tin(Sn) atoms in the lattice of CIS. Thin films were deposited on ITO glass substrates using a compact target which were made by $Cu_2$S, ZnS, SnS$_2$ powder at room temperature by rf magnetron sputtering and were annealed in the atmosphere of Ar and $S_2$(g). We investigated potentialities of a low-cost material for the solar cell by measuring of thin film composition, the structure and optical properties. We could get an appropriate $Cu_2$$ZnSnS_4$ composition. Structure was coarsened with increasing temperature and (112), (200), (220), (312) planes appeared to conform to all the reflection Kesterite structure. A (112) preferred orientation was advanced with increasing the annealing temperature as shown in the diffraction peaks of the CIS cells and was available for photovoltaic thin film materials. The band gap increased from 1.51 to 1.8eV as the annealing temperature increased. The optical absorption coefficient of the thin film was about $10^4$$cm^{-1}$.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.271-272
• /
• 2012

Bulk Metallic Glasses (BMGs or amorphous alloy) exhibit high strength and good corrosion resistance. Applications of thin films and micro parts of BMGs have been used a lot since its inception in the research of BMGs. However, Application and fabrication of BMGs are limited to make structural materials. Thin films of BMGs which is sputtered on the surface of structural materials by sputtering process is used to improve limits about application of BMGs. In order to investigate the difference of properties between designed alloys and thin films, we identified that thin films deposited on the surface that have the characteristic of the amorphous films and the composition of designed alloys. Zr-Cu (Cu=30, 35, 38, 40, 50 at.%) and Zr-Cu-Al (Al=10 at.% fixed, Cu=26, 30, 34, 38 at.%) alloys were fabricated with Zr (99.7% purity), Cu (99.997% purity), and Al (99.99% purity) as melting 5 times by arc melting method before rods 2mm in diameter was manufactured. In order to analyze GFA (Glass Forming Ability), rods were observed by Optical Microscopy and SEM and $T_g$, $T_x$, ($T_x$ is crystallization temperature and $T_g$ is the glass transition temperature) and Tm were measured by DTA and DSC. Powder was manufactured by Gas Atomizer and target was sintered using powder in large supercooled liquid region ($=T_x-T_g$) by SPS(Spark Plasma Sintering). Amorphous foil was prepared by RSP process with 5 gram alloy button. The composition of the foil and sputtered thin film was analyzed by EDS and EPMA. In the result of DSC curve, binary alloys ($Zr_{62}Cu_{38}$, $Zr_{60}Cu_{40}$, $Zr_{50}Cu_{50}$) and ternary alloys ($Zr_{64}Al_{10}Cu_{26}$, $Zr_{56}Al_{10}Cu_{34}$, $Zr_{52}Al_{10}Cu_{38}$) have $T_g$ except for $Zr_{70}Cu_{30}$ and $Zr_{60}Al_{10}Cu_{30}$. The compositions with $T_g$ made into powders. Figure shows XRD data of thin film showed similar hollow peak.

• 한국진공학회지
• /
• 제14권4호
• /
• pp.238-244
• /
• 2005

rf 마그네트론 스퍼터링 방법을 사용하여 유리기판 위에 $In_2O_3$ : ZnO=90 : 10 $wt.\%$의 조성비를 갖는 indium-zinc-oxide(IZO) 박막을 산소분압 $O_2$/(Ar +$O_2$) : $0\~10 \%$의 Ar가스 분위기에서 제작하였다. IZO 박막의 면저항은 증착 시 유입되는 산소량이 증가함에 따라 현저하게 증가하는데, 순수한 Ar 가스 분위기에서 증착될 때 $3.7\times10^{-4}\Omega\cdot$ cm 정도의 가장 낮은 비저항과 가시광 영역에서 평균 $85\%$ 이상의 투과율을 보이는 박막이 얻어진다. $600^{\circ}C$의 다양한 환경에서 옅처리될 경우, 순수한 Ar 분위기에서 성막된 IZO 박막의 전기적 저항 변화는 박막 내에 포함된 In 또는 InO와 같은 금속 성분들의 결정화와 산화에 의해 설명되어 진다. 또한 IZO 박막을 공기 중에서 열처리하는 동안 $600^{\circ}C$ 이상에서 현저하게 일어나는 산소 흡착과 구조 변화에 의한 전기적 특성들이 조사된다.