• 한국재료학회지
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• 제23권6호
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• pp.316-321
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• 2013

The electrical properties and surface morphology changes of a silicon wafer as a function of the HF concentration as the wafer is etched were studied. The HF concentrations were 28, 30, 32, 34, and 36 wt%. The surface morphology changes of the silicon wafer were measured by an SEM ($80^{\circ}$ tilted at ${\times}200$) and the resistivity was measured by assessing the surface resistance using a four-point probe method. The etching rate increased as the HF concentration increased. The maximum etching rate 27.31 ${\mu}m/min$ was achieved at an HF concentration of 36 wt%. A concave wave formed on the wafer after the wet etching process. The size of the wave was largest and the resistivity reached 7.54 $ohm{\cdot}cm$ at an 30 wt% of HF concentration. At an HF concentration of 30 wt%, therefore, a silicon wafer should have good joining strength with a metal backing as well as good electrical properties.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.35.1-35.1
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• 2009

Vertically aligned zinc oxide (ZnO) nanorods (NRs) with different surface morphology were grown by metal organic chemical vapor deposition (MOCVD) on sapphire substrate. The films thus prepared were characterized by measuring X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) studies. To study the effect of surface morphology on wettability, the contact angle (CA) of water was measured. It was demonstrated that the CA of the deposited ZnO NRs varied between $104^{\circ}$ and $135^{\circ}$ depending upon the surface morphology. Variable temperature photoluminescence (PL) have employed to probe the exciton recombination in high density and vertically aligned ZnO Nanorod arrays. The low-temperature PL characterizes the dominant near-band-edge excitonic emissions from such nanorod arrays.

• 한국재료학회지
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• 제17권5호
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• pp.283-288
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• 2007

This study aimed to investigate the effects of the seed layer with copper electroplating on the surface morphology of copper foil. Three kinds of seed metal such as platinum, palladium, Pt-Pd alloy were used in this study. Electrodeposition was carried out with the constant current density of 200 $mA/cm^2$ for 68 seconds. Electrochemical experiments, in conjunction with SEM, XRD, AFM and four-point probe, were performed to characterize the morphology and mechanical characteristics of copper foil. Large particles were observed on the surface of the copper deposition layer when a copper foil was electroplated on the 130 nm thickness of Pd, Pt-Pd seed layer. However, a homogeneous surface, low resistivity was obtained when the 260 nm thickness of Pt, Pt-Pd alloy seed layer was used. The minimum value of resistivity was 2.216 ${\mu}{\Omega}-cm$ at the 260 nm thickness of Pt-Pd seed layer.

• 한국재료학회지
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• 제12권1호
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• pp.10-15
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• 2002

Melt blends of maleic anhydride grafted polypropylerle(PP-g-MA) and Nylon 6 were prepared to study the influence of chemical reaction between the two polymer components. By adding the MA grafted polystyrene pold (ethylene/butadiene) and polystyrene[SEBS-g-MA] as the compatible modifiers to reinforce the impact resistance, the Izod impact strength, high rate impact strength and morphology were studied. The notched Izod impact strength increased with the content of PP-g-MA and SEBS- g-MA. The energy of high rate impact strength increased as the thickness of specimen increased, while, it increased as the specimen displacement decreased. In the morphology observed by SEM, finally, we confirmed the improvement of the compatibilization and interfacial adhesion with the content of SEBS-g-MA. The continuous phase of PP-g-MA was the main cause of the modified properties.

• 한국재료학회지
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• 제14권2호
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• pp.121-125
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• 2004

Nickel oxide (NiO) thin films were deposited on Si(100) substrates at room temperature by RF magnetron sputtering from a NiO target. The effects of plasma gas and RF power on the crystallographic orientation and surface morphology of the NiO films were investigated. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were employed to characterize the deposited film. It was found that the type of plasma gases affected the crystallographic orientation, deposition rate, surface morphology, and crystallinity of NiO films. Highly crystalline NiO films with (100) orientation were obtained when it was deposited under Ar atmosphere. On the other hand, (l11)-oriented NiO films with poor crystallinity were deposited in $O_2$. Also, the increase in RF power resulted in not only higher deposition rate, larger grain size, and rougher surface but also higher crystallinity of NiO films.

• 폴리머
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• 제24권3호
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• pp.366-373
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• 2000

본 연구에서는 poly(phenylene sulfide)(PPS)와 ABS의 물성을 상호보완하기 위하여 블렌드를 제조하였다. 각 성분간의 상용성을 증진시키기 위하여 소량의 무수말레인산을 ABS에 반응시켜 MABS (ABS-g-MAH)를 제조하였으며, PPS/ABS 및 PPS/MABS 블렌드는 이축 혼련 압출기를 이용하여 용융 흔합하였다. 블렌드에서 ABS의 화학적 개질이 블렌드의 모폴로지와 열적 성질에 미치는 영향을 관찰하였다. PPS/MABS 블렌드의 경우, 각 성분간에 강한 인력이 형성되는 것을 광학현미경과 SEM을 이용하여 확인하였으며, DMA 분석에서는 단일 유리전이 온도를 확인하였다. 또한 화학적으로 개질된 MABS를 사용한 PPS/MABS의 블렌드는 PPS/ABS보다 향상된 열적 성질을 나타내었다.

• 식물분류학회지
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• 제48권2호
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• pp.134-142
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• 2018

The achene morphology of 21 taxa of Persicaria sect. Cephalophilon including the related taxa of Koenigia (Polygonaceae) was examined using stereo microscopy and scanning electron microscopy to evaluate its diagnostic values and taxonomic implications. The outlines of achene were narrowly ovoid to broadly ovoid in general, and elliptic achenes were observed in Koenigia taxa, with the achene shape being biconvex or trigonous. The size of the P. sect. Cephalophilon taxa ranged from $0.93-3.55{\times}0.80-2.31mm$ and the size of examined Koenigia taxa ranged from $1.10-1.84{\times}0.79-1.02mm$. The smallest achenes in P. sect. Cephalophilon were observed in P. humilis and the largest achenes were found in P. chinensis var. chinensis. Furthermore, infraspecific taxa of P. chinensis had relatively large achenes compared to other taxa within the section. Most taxa of P. sect. Cephalophilon had dull achenes, while four taxa had glossy achenes (P. capitata, P. runcinata var. runcinata, P. runcinata var. sinensis, and P. sinuata). Four types of surface patterns (smooth, tubercles, small pits, and irregular ridge) were observed, and the tubercles were divided into two subtypes according to the grouping and distribution pattern. The achene morphology of P. sect. Cephalophilon is described and compared, and its taxonomic implications are also discussed.

• Structural Engineering and Mechanics
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• 제76권5호
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• pp.561-578
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• 2020

The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under nanofluid assisted minimum quantity lubrication (NFMQL) condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles enriched eco-friendly radiator coolant based nano-cutting fluid for machinability improvement of hardened steel. Combined approach of central composite design (CCD) - analysis of variance (ANOVA), desirability function analysis, and response surface methodology (RSM) have been subsequently employed for experimental investigation, predictive modelling and optimization of surface roughness. With a motivational philosophy of "Go Green-Think Green-Act Green", the work also deals with economic analysis, and sustainability assessment under environmental-friendly NFMQL condition. Results showed that machining with nanofluid-MQL provided an effective cooling-lubrication strategy, safer and cleaner production, environmental friendliness and assisted to improve sustainability.

• 한국재료학회지
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• 제22권2호
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• pp.78-81
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• 2012

$Y_2O_3$ nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently, many studies have focused on controlling the size and morphology of $Y_2O_3$ in order to obtain better material performance. $Y_2O_3$ powders were prepared under a modified solvothermal condition involving precipitation from metal nitrates with aqueous ammonium hydroxide. The powders were obtained at temperatures at $250^{\circ}C$ after a 6h process. The properties of the $Y_2O_3$ powders were studied as a function of the solvent ratio. The synthesis of $Y_2O_3$ crystalline particles is possible under a modified solvothermal condition in a water/ethylene glycol solution. Solvothermal processing condition parameters including the pH, reaction temperature and solvent ratio, have significant effects on the formation, phase component, morphology and particle size of yttria powders. Ethylene glycol is a versatile, widely used, inexpensive, and safe capping organic molecule for uniform nanoparticles besides as a solvent. The characterization of the synthesized Y2O3 powders were studied by XRD, SEM (FE-SEM) and TG/DSC. An X-ray diffraction analysis of the synthesized powders indicated the formation of the $Y_2O_3$ cubic structure upon calcination. The average crystalline sizes and distribution of the synthesized $Y_2O_3$ powders was less than 2 um and broad, respectively. The synthesized particles were spherical and hexagonal in shape. The morphology of the synthesized powders changed with the water and ethylene glycol ratio. The average size and shape of the synthesized particles could be controlled by adjusting the solvent ratio.

• 마이크로전자및패키징학회지
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• 제11권3호
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• pp.47-53
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• 2004

공정 Au-20Sn 솔더합금을 솔더링 시간과 온도를 달리하여 Ni위에서 솔더링하였다. 주사전자현미경 (SEM)을 사용하여 계면에 생성된 IMC의 조성, 상, 모양에 대해 조사하였다. 계면에는 $(Au,Ni)_3Sn_2$와 $(Au,Ni)_3Sn_2$의 두 가지 IMC가 생성되었다. 그 중 첫 번째 생성된 IMC인 $(Au,Ni)_3Sn_2$상은 솔더링 온도에 따라 모양의 변화가 관찰되었다. 이러한 모양의 변화로 인한 확산통로수의 변화는 모든 솔더링 온도에서 거의 비슷한 IMC 두께를 가지도록 한다. IMC, $(Au,Ni)_3Sn_2$상의 모양변화는 온도 증가에 의한 생성엔탈피의 감소 때문인데, 이는 Jackson's parameter로써 잘 설명될 수 있다.