• Computers and Concrete
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• 제10권1호
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• pp.19-33
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• 2012

The performance of a concrete is significantly influenced by its mixture proportion and the coating thickness on aggregate surface. The concrete in this study is designed by estimating the blending ratio of aggregate using a densified mixture design algorithm (DMDA) based on an ideal grading curve and estimating the paste volume as the sum of the amount of paste needed to provide an assigned coating paste thickness. So as to obtain appropriate concrete amount, and thus can accurately estimate the property of concrete. Deduction of this mix design formula is simple and easy understanding, and meanwhile to obtain result is fast. This estimation model of mix design is expected to reward to industry and effectively upgrade concrete quality.

• 한국광학회지
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• 제11권4호
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• pp.255-260
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• 2000

유기 금속화합물을 출발물질로 이용하는 졸-겔 방법으로 균열이 없는 유기-무기 복합 실리카 박막을 제작하였으며, 코팅방법, 조성비, prebake, postbake 온도 등의 제작조건에 따른 박막의 두께 및 굴절률의 변화를 체계적으로 조사하여 재현성 있는 제작조건을 확립하였다. 특히 광개시제를 첨가하였을 때 자외선 노광량에 따른 광학적 성질변화를 세 가지 광개시제에 대하여 측정, 비교하였다. 또한 졸-겔 박막으로 다중모드 간섭을 이용한 광 파워 분배기를 제작하여 광소자로의 응용 가능성을 살펴보았다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.102.2-102.2
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• 2012

Different layers of zirconium nitride (ZrN) and hydroxyapatite (HA) coatings were prepared on cp Ti substrate for biomedical applications. The main idea is to improve the mechanical strength as well as the biocompatibility of the coating. ZrN is known for its high mechanical strength, corrosion resistance. HA is well known for its biocompatibility properties. Hence, in this study, both materials were coated on a cp Ti substrate with bottom layer with ZrN for good bonding with substrate and the top layer with HA for induce bioactivity. Middle layer was formed by a composite of HA and ZrN. Detail analyses of the layered coatings for its structural, morphological, topographical properties were carried out. Then the mechanical property of the layered coatings was analyzed by nanoindentation. Biomimetic growths of apatite on the functionally graded coatings were determined by simulated body fluid method. This study provides promising results to use this kind of coatings in biomedical field.

• 한국신뢰성학회지:신뢰성응용연구
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• 제1권2호
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• pp.95-108
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• 2001

To enhance the corrosion resistance of a bolt by surface treatment, dacrotization was considered as a substitute for phosphate coating which is widely used for general applications. In this study, comparisons were made among 5 different kinds of surface treatments including dacrotization and phosphate coating with respect to corrosion resistance, adhesion property with painting, and preload when tightened. The result shows that the dacrotized and surface-stabilized bolt is much superior in every aspects studied herein to others. An excellent corrosion resistance and a fairly good adhesion property with painting were achieved in the dacrotized and surface-stabilized bolt. When tightened at the same torque, the amount of preload and its deviation of dacrotized and surface-stabilized bolt were comparable with those of phosphate coated bolt.

• Corrosion Science and Technology
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• 제2권2호
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• pp.102-108
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• 2003

The surface treatments. Chrome/Manganese and Modified Chrome Pickle, that are treated to improve the anti-corrosion property which is needed to increased the probability of prototype product enabled the sand cast Magnesium test specimens to have better corrosion resistance than non-treated one. Sand cast Magnesium specimens which was treated only with chemical conversion coating had same corrosion resistance with the Steel specimens plated by Zinc, and the another one that had the finishing treatment(painting) worked on the chemical surface treatment had the corrosion resistance property to meet to FPO-3 requirement. We also investigated the multiple finishing system(chemical surface treatment + 3 coating) to test the severe condition that magnesium should to endure.

• 한국의류산업학회지
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• 제14권4호
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• pp.635-640
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• 2012

In this study, thermoplastic urethane (TPU) coating yarns were prepared at various extruding temperatures. The fine structure and mechanical properties of resultant TPU coating yarns examined by the wide angle X-ray diffractometer (WAXD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile test. TPU coating yarns (prepared at extruding temperatures at $175^{\circ}C$) were confirmed as a stable fine structure that obtained excellent tensile strength and flexibility. The C samples prepared by optimized conditions made by TPU woven floor mat. The structure of the woven mat is $4{\times}4$ basket weave and have laminated with the EVA foam to obtained final TPU woven floor mat products. The resultant TPU woven floor mat was obtained to 1.5MN of tensile strength, 22% of the elongation, and 0.2MN of tear strength. The weight loss abrasion and the resilience by the ball rebound of the TPU-woven floor mat was prior to those of the PVC subsequently, we were able to develop a woven floor mat with TPU coating yarn and produce an eco-friendly high valuable woven floor mat using an interior product.

• 펄프종이기술
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• 제35권3호
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• pp.21-28
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• 2003

It is essential to use base papers having proper surface characteristics in coating operation for improving coated paper quality and coater runnability. To fulfill these purposes surface sizing of coating base stock with anionic oxidized starch is commonly practiced. It is suggested that use of cationic starch for surface sizing rather than conventional oxidized starch will improve coated paper quality since cationic starch penetrates less into paper structure because of its strong electrostatic interaction with anionically charged paper surface. Strong interaction of cationic surface sizing starch with anionic coating color is expected to promote rapid immobilization of the coating color and improve coating holdout and optical property. The immediate objective of this study was to examine the influence of surface sizing starches on the properties of coated papers. Structural characteristics of the coatings formed on the substrate surface sized with cationic and anionic starches were examined. To enhance the efficiency of cationic surface sizing starch on coated paper properties, strongly charged cationic polymers were added to the surface sizing starch and its effect on coated paper properties was evaluated. Results showed that opacity and light scattering coefficient of coated paper were higher when base paper surface sized with cationic starch was used. Addition of less than 1% of cationic poly-DADMAC to the cationic surface sizing starch improved the opacity of coated paper significantly.

• 한국재료학회지
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• 제27권2호
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• pp.119-126
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• 2017

WC-CrC-Ni coatings were prepared by nine processes of the Taguchi program with three levels for the four spray parameters: spray distance, flow rates of hydrogen and oxygen, and powder feed rate. The optimal coating process (OCP) was oxygen flow rate of 38 FMR, hydrogen flow rate of 53 FMR, powder feed rate of 25 g/min, and spray distance of 7 inches. Hardness of 1150 Hv and porosity of 1.2 %, were obtained by OCP; these are better results compared with the highest 1033 Hv and the lowest 1.5 % porosity obtained by nine processes of the Taguchi program. Friction coefficient of the WC-CrC-Ni coating decreased from $0.36{\pm}0.07$ at $25^{\circ}C$ to $0.23{\pm}0.07$ at $450^{\circ}C$. These values were smaller than those of the EHC (electrolytic hard chrome) plating at both temperatures due to lubrication from the oxide debris. The wear trace and wear depth of the coating are smaller than those of the EHC at both temperatures. Pitting was not found in the WC-CrC-Ni coating sample, while it did appear in the EHC sample.

• Environmental Engineering Research
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• 제24권4호
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• pp.646-653
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• 2019

Recovery of valuable metals in the industrial wastewater and sludge has attracted an attention owing to limited metallic resources in the earth. In this study, we firstly fabricated Ti/Ir-Ru electrodes by spin coating technique for effective recovery of Cu in electrowinning process. Two different Ti/Ir-Ru electrodes were fabricated using 100 and 500 mM of precursors (i.e., Ir-Ru). SEM-EDX and AFM revealed that Ir and Ru were homogenously distributed on the surface of Ti plate by the spin coating, in particular the electrode prepared by 500 mM showed distinct boundary line between Ir-Ru layer and Ti substrate. XRD, XPS, and cyclic voltammetry also revealed that characteristics of IrO₂, RuO₂, and TiO₂ and its electrocatalytic property increased as the concentration of coating precursor increased. Finally, we carried out Cu recovery experiments using two Ti/Ir-Ru as anodes in electrowinning process, showing that both anodes showed a complete removal of Cu (1 and 10 g/L) within 6 h reaction, but much higher kinetic rate constant was obtained by the anode prepared by 500 mM. The findings in this study can provide a fundamental knowledge for surface characteristics of Ti/Ir-Ru electrode prepared by spin coating method and its potential feasibility for effective electrowinning process.

• 한국표면공학회지
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• 제52권6호
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• pp.350-356
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• 2019

In this study, the effect of mechanical polishing of carbon steel on the tribological properties of manganese phosphate coating on carbon steel has investigated. The microstructure, surface morphology and chemical composition were analyzed by SEM, EDS, and XRD. The surface roughness test was carried out in order to calculate Rvk value by 3D laser microscopy. Also, the tribology property of manganese phosphate coating was tested by ball-on disk. In the results of EDS analysis, coating layer consists of elements such in Mn, P, Fe, and O. XRD showed that (Mn,Fe)₅H₂(PO₄)₄·4H₂O in manganese phosphate coating layer was formed by the chemical reaction between manganese phosphate and elements in carbon steel. As the mechanical polishing degree increased, the friction coefficient was reduced. The rougher the mechanical polishing degree, the better corrosion resistance was obtained.