• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3805-3810
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• 2013

The surface modification of silica particles (SPs) was systemically conducted by the treatment of 0.1-10 wt % phenylsilanetriol (PST) on the basis of SPs used through two step processes: 1) the PST coating of SPs via evaporation under reduced pressure and 2) their thermal condensation leading to Si-O-Si bond formation via heating at $130^{\circ}C$. The evaluation of the modified SPs was conducted by the simple floating test on water and the measurement of the contact angle (CA) of water droplet on the 2-dimensional layer of modified SPs on slide glass. When PST was used about 2 wt % or above on the basis of SPs (about average size: 50 nm) used, the modified SPs were fully floated on the water and all dispersed into upper organic solvent layer after a shaking with the mixture of the water and benzene, indicating that the modified SPs have hydrophobic properties. The modified SPs were characterized by $^{29}Si$ MAS NMR and physicochemical properties including SEM, TEM, BET, adsorption/desorption isotherms, etc. were measured and compared each other in details. This research demonstrates that the organosilanetriol is a good modifier applicable for the surface modification of inorganic oxide particles using a low amount of modifier on the basis of oxide particles used.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.308-319
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• 2005

Piezo-ceramics are special materials which transform energy between mechanical and electrical forms. Bender-elements are composite materials consisting of thin piezo-ceramics and elastic shims, and are widely used as actuators and transducers in the field of electronics, robotics, autos and mechatronics utilizing the effectiveness of energy transformation capability. In geotechnical engineering, commercial bender-elements are used in laboratory as source and receiver in the measurements of soil stiffness. The elements were built by using various metal shims sandwiched between piezo-ceramics and coating over the composite in the research. A pair of elements were buried in a concrete block and used as source and receiver to measure the stiffness of the concrete. The test results were verified by comparing with the resonant column testing results. In a preliminary stage of the development of an in-situ seismic testing equipment using bender-elements for soft clay materials, shear waves were generated and measured by burying the elements in the barrel of kaolinite and water mixture. The measured shear wave signals were so distinct for the first-arrival pick that applicability of the elements in the field measurements is very promising.

• 한국전기전자재료학회논문지
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• 제18권7호
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• pp.662-666
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• 2005

Silicon nitride $(SiN_x)$ film is a promising material for anti-reflection coating and passivation of multicrystalline silicon (me-Si) solar cells. In this work, a plasma-enhanced chemical vapor deposition (PECVD) system with batch-type reactor tube was used to prepare highly robust $SiN_x$ films for screen-printed mc-Si solar cells. The Gas flow ratio, $R=[SiH_4]/[NH_3]$, in a mixture of silane and ammonia was varied in the range of 0.0910.235 while maintaining the total flow rate of the process gases to 4,200 sccm. The refractive index of the $SiN_x$ film deposited with a gas flow ratio of 0.091 was measured to be 2.03 and increased to 2.37 as the gas flow ratio increased to 0.235. The highest efficiency of the cell was $14.99\%$ when the flow rate of $SiH_4$ was 350 sccm (R=0.091). Generally, we observed that the efficiency of the mc-Si solar cell decreased with increasing R. From the analysis of the reflectance and the quantum efficiency of the cell, the decrease in the efficiency was shown to originate mainly from an increase in the surface reflectance for a high flow rate of $SiH_4$ during the deposition of $SiN_x$ films.

• Advances in materials Research
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• 제7권1호
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• pp.73-81
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• 2018

$TiO_2/CH_3NH_3Pb_{1-x}Sb_xI_{3-3x}Br_{3x}-based$ photovoltaic devices were fabricated by a spin-coating method using mixture solutions with $SbBr_3$. Effects of $SbBr3$, CsI or RbBr addition to $CH_3NH_3PbI_3$ precursor solutions on the photovoltaic properties where investigated. The short-circuit current densities and photoconversion efficiencies were improved by adding a small amount of $SbBr_3$, CsI or RbBr to the perovskite phase, which would be due to the doping effect of Sb, Br and Cs/Rb atom at the Pb, I and $CH_3NH3$ sites, respectively.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.741-744
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• 2002

Single phase of multicomponent oxide ZrTiO4 film could be prepared through surface sol-gel route simply by coating the mixture of 100 mM zirconium butoxide and titanium butoxide on $Pt/Ti/SiO_2Si(100)$ substrate, following pyro lysis at $450^{\circ}C$, and annealing it at 770 $^{\circ}C.$ The dielectric constant of the film was reduced as the film thickness decreased due to of the interfacial effects caused by layer/electrode and a few voids inside the multilayer. However, the dielectric property was independent of applied dc bias sweeps voltage (-2 to +2 V).The dielectric constant of bulk film, 31.9, estimated using series-connected capacitor model was independent of film thickness and frequency in the measurement range, but theoretical interfacial thickness, ti, was dependent on the frequency. It reached a saturated ti value, $6.9{\AA}$, at high frequency by extraction of some capacitance component formed at low frequency range. The dielectric constant of bulk ZrTiO4 pellet-shaped material was 33.7 and very stable with frequency promising as good applicable devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.161-161
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• 1999

In the field of material science, the interests and efforts to modify the surface of materials in agreement with the need of usage have been extensively increasing. he modification to improve the wettability of surface is very important is terms of adhesion, printing, etc. It is very difficult to modify metal surface into hydrophilic one. therefore, surfactant coating has been generally used in many cases. However, surfactant has disadvantages such as environmental problem, soluble in water. in this study, hydrophilic polymer films as alternative of surfactant were deposited on metal substrate by DC plasma polymerization. Hydrophilic polymer films deposited by DC plasma show many merits such as good wettability, stone adhesion to substrate, high resistance to most chemicals. Monomer gas and reactive gas were used as source plasma polymerization. Plasma polymerized films were fabricated with process parameters of deposition time, ratio of gas mixture, current, pressure, etc. Effects of these variables on wettability of plasma polymer films will be discussed. With XPS and FT-IR analyses of plasma polymeric films, the relation between wettability and chemical state of polymer films by DC plasma was investigated.

• 펄프종이기술
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• 제47권5호
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• pp.127-133
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• 2015

Recent worldwide trends are to develop the environmental friendly chemicals and processes in order to reduce the global warming and climate change phenomena. One of similar efforts in paper industry is to substitute the petroleum-based SBR latex by starch-based biobinder. The disadvantage of biobinder found through laboratory scale study was the lower dry pick strength than SBR latex. The objective of this study is to confirm the substitutability of SBR latex with biobinder through mill trial. Although biobinder itself gave lower dry pick strength, it was found that the use of SBR latex and biobinder mixture (50:50) could improve the dry pick strength. The introduction of biobinder into coating binder system improved the opacity of coated paper. Optical properties (brightness and whiteness), ink trapping, print gloss and mottling level of paper coated with biobinder system were similar to those of SBR latex.

• 한국의류산업학회지
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• 제6권5호
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• pp.667-672
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• 2004

Poly(ethylene terephthalate) (PET) fabrics were treated with a silica particle and phosphate flame retardant to determine the optimum process condition of the digital textile printing(DTP) media. The treating conditions for the study were 6 conditions, from F1 to F6, in which F3, F4 and F5 were treated with mixture of both silica particle and phosphate compound in process of pad, dry and cure fixation. F6 was treated with phosphate compound only and silica particle coating successively. Xanthan gum was used to control the migration of liquid phosphate compound onto PET fabrics. The change in surface morphology of fabrics treated with silica particle and phosphate compound was observed by SEM and flame retardance was evaluated by limiting oxygen index(LOI). It was observed that F6 was the excellent flame retardance and low bleeding in printing, Collectively, the printing characteristics of silica to cyan, magenta, yellow and black ink and flame retardance of fabrics finished with phosphate compound were identified in this study.

• 한국분말재료학회지
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• 제8권3호
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• pp.201-206
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• 2001

$>LaMnO_3$$(La, Sr)MO_3$, and $(La, Sr)MO_3/YSZ$ gel films were deposited by spin-coating technique on scandium-doped zirconia (YSZ) substrate using the precursor solution prepared from $La(O-i-C_3H_7)_3$, $Co(CH_3COO)_2$or $Mn(O-i-C_3H_7)_2$,2-methoxyethanol, and polyethylene glycol. By heat-treating the gel films, the electrochemical cells, $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ were fabricated. The effect of polyethylene glycol on the microstructure evolution of $$LaCoO_3and $LaMnO_3$thin films was investigated, and NOx decomposition characteristics of the electrochemical cells were investigated at $500^{\circ}C$ to $600^{\circ}C$. By applying a direct current to the $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ electrochemical cell, good NOx conversion rate could be obtained relatively at low current value even if excess oxygen is included in the reaction gas mixture.

• 한국표면공학회지
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• 제40권6호
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• pp.279-282
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• 2007

Cr-Mo-Si-C-N coatings were deposited on steel and Si wafer by a hybrid system of AIP and sputtering techniques using Cr, Mo and Si target in $Ar/N_2/CH_4$ gaseous mixture. Instrumental analyses of XRD and XPS revealed that the Cr-Mo-Si-C-N coatings must be a composite consisting of fine(Cr, Mo and Si)(C and N) crystallites and amorphous $Si_3N_4$ and SiC. The hardness value of Cr-Mo-Si-C-N coatings significantly increased from 41 GPa of Cr-Mo-C-N coatings to about 53 GPa with Si content of 9.3 at.% due to the refinement of (Cr, Mo and Si)(C and N) crystallites and the composite microstructure characteristics. A systematic investigation of the microstructures and mechanical properties of Cr-Mo-Si-C-N coatings prepared with various Si contents is reported in this paper.