• 펄프종이기술
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• 제47권2호
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• pp.9-16
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• 2015

High loading of base paper is regarded as one of reasons to aggravate fold cracking of coated paper. But the relationship between the ash content of base paper and fold cracking of coated paper has not been shown yet. We investigated the effect of ash content in base paper on the fold cracking of coated paper. Handsheets with three different ash contents (19.5-23.5%) were prepared, and double layered coating were applied on the top side of the handsheets. A gravimetric water retention meter (AA-GWR) was employed to fold the paper with a uniform pressure after solid printing on the coated surface. The fold cracking was digitized by calculating the cracked area by means of an image analysis technique. Results suggested that high ash content in the base paper increased the fold cracking of the outer surface of coated papers. In the case of inner surface greater fold crack areas were obtained, and the number of cracks decreased because long and wide cracks were formed. Reduction in tensile strength and thickness appeared to give greater fold cracking for highly loaded papers.

• Carbon letters
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• 제7권4호
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• pp.259-265
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• 2006

Carbon-coated $TiO_2$ was prepared by $CCl_4$ solvent mixing method with the different heat treated temperatures (HTTs). Since the carbon layers derived from pitch on the $TiO_2$ particles were porous, the carbon-coated $TiO_2$ sample series showed a good adsorptivity. The values of BET surface areas measured were shown independently on the HTTs. The surface states by SEM present to the characterization of porous texture on the carbon-coated $TiO_2$ sample and carbon distributions on the surfaces. From XRD data, PT700 and PT750 were shown the X-ray diffraction patterns of the anatase $TiO_2$, but PT800 and PT850 were kept anatase-type structure even after heating at $800^{\circ}C$, though small amount of the rutile-type structure appears. The results of EDX microanalyses were observed for each sample show the spectra corresponding to almost all samples similar to C, O and Ti elements with an increase of HTTs. Finally, the excellent photoactivity of carbon-coated $TiO_2$ (especially, PT700 and PT750) could be attributed to the homogeneous coated carbon on the external surface and the structural anatase phase.

• Fibers and Polymers
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• 제2권3호
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• pp.148-152
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• 2001

Cotton yarns were coated with a polymer solution to hold surface fibers to the yam body, which caused fiber-fly generation during knitting process. The physical property of the coated yarn, especially a bending rigidity was investigated in order to evaluate the performance of the coated yam during knitting. SEM images showing the surface condition of the coated yarn demonstrated that the thickness of a coating material increased as the concentration of the coating solution increased. The results of the bending rigidity measured using KES-FB2 system showed that the bending rigidity of the coated yam increased as the concentration of the coating solution increased. The results also revealed the possibility that yarn coated with a low amount of coating material should be employed for further research of reducing fiber-fly generation during knitting process.

• 한국표면공학회지
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• 제33권1호
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• pp.17-24
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• 2000

The microstructures and corrosion properties of Al-Si diffusion coated PWA1426 and PWA658 alloys have been investigated. The coated layer and corrosion properties were analysed by SEM, EDS and hot corrosion test. According to the results of SEM, it is supposed that the coated layers were composed of mixed, denuded and inter-diffusion layer. The coated PWA1426 alloy improved corrosion properties, compared to the PWA658 alloy. Corrosion debris generated during hot corrosion test of PWA658 alloy are identified as NiO, $TiO_2$and $NiAl_2$$O_4$from coated layer which increase oxidation rate and decrease adhesion. The PWA1426 alloy heat treated at $1080^{\circ}C$ showed that NiAl and $Al_2$$O_3$formed on coated layer.

• 약학회지
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• 제39권6호
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• pp.593-599
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• 1995

Erythromycin was formulated as enteric-coated pellets in order to reduce degradation in stomach and gastromtestmal irritation, and to maximize the absorption in intestine followmg its oral administration. Core pellets were prepared using fluid-bed granulator with two different methods (powder layering and solvent spraying) and enteric-coated with two different coating polymers (HPMCP and Eudragit E30D). Physical characteristics md dissolution rates of core pellets and enteric-coated pellets were evaluated to optimize the formulation. Powder layering method resulted in shorter initial dissolution time than solvent spraying method, but physicochmical properties of the product were worse than solvent spraying method with respect to hardness, ftiability and density. The dissolution rate of the drug was increased with the addition of surfactants, showing concentration-dependence. The scanning electron microscopic observation of pellets revealed significant differences on the surface appearances prepared with solvent spraying method. The core pellet made with powder layering method had crystals on the surface, which resulted in poor physical properties of the pellets. The dissolution profiles of erythromycin pellets coated with HPMCP or Eudragit L30D were close to that of commercially available erythromycin enteric-coated product.

• 소성∙가공
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• 제15권5호
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• pp.366-372
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• 2006

The effect of coating time in arc ion plating on surface properties of the TiN-coated high speed steel(SKH51) is presented in this paper. Surface roughness, micro-hardness, coated thickness, atomic distribution of TiN and adhesion strength are measured for various coating times. It has been shown that the coating time has a deep influence on the micro-hardness, the coated thickness, the atomic distribution of Ti and the adhesion strength of the SKH51 steels but that it has little influence on the surface roughness.

• 한국기계가공학회지
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• 제10권5호
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• pp.44-50
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• 2011

The effect of deposition time in arc ion plating on surface properties of the TiN-coated SM45C steel is presented in this paper. The surface roughness, micro-particle, micro-hardness, coated thickness, atomic distribution of TiN, and adhesion strength are measured for various deposition times. It has been shown that the deposition time has a considerable effect on the micro-hardness, the coated thickness, and the atomic distribution of TiN of the SM45C steels but that it has little influence on the surface roughness and adhesion strength.

• 한국기계가공학회지
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• 제19권3호
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• pp.8-13
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• 2020

Carbon fiber-reinforced plastics (CFRPs) are extremely strong and light fiber-reinforced plastics containing carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and rigidity are required, such as in the aerospace, automotive, and ship superstructure industries. In CFRP drilling, the tool performance greatly varies depending on the tool shapes, cutting conditions, and diamond coating. This study developed a new type of tungsten carbide drill with multi-blade edges to evaluate the surface quality of CFRP materials according to the coating thickness of diamond-coated drills. Experiments on tool wear, surface roughness, and burr formation were conducted. The bore exit quality of a 12 mμ -coated drill was better than that of a 6 mμ -coated drill. The superior effects of the 12 mμ -coated drill and the good surface quality of CFRP were also demonstrated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.241-244
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• 2004

The evaluation of Single or multi-degregation of concrete coated by high performance surface penetration agency was examined through various tests, i.e., carbonation, absorption, carbonation + chloride ion and carbonation + chemical solution according to various high performance surface penetration agencies and various compressive strengths of base concrete. The 2 types of high performance surface penetration agencies were used i.e., inorganic and alcohol soluble. And 2 types of compressive strength of base concrete were used such as 21 30. MPa. The characteristics of concrete coated high performance surface penetration agency was more improved than that of non-coated concrete, and especially, water soluble inorganic agency was most effective. And if compressive strength of base concrete was low, the improved effects would be larger.

• 한국세라믹학회지
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• 제37권4호
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• pp.338-344
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• 2000

Grain boundary chemistry and electrical characteristics of polycrystalline BaTiO3 ceramics, which were prepared with sol-gel surface-coated semiconducting powders, were investigated. Mn ions were coated on the powder surface by sol-gel coating-techniques. The additives coated on the surface of the powders were observed to be present near the grain boundaries of the ceramics. The ceramics exhibit the PTCR characteristics with a resistivity jump ratio(Pmax/Pmin) of about 2$\times$103. With raising the temperature from room temprature to 20$0^{\circ}C$, the oxidation state of the Mn ions varied from Mn3+ to Mn2+ in the coating layers. Near the grain boundaries an excessive negative charge layer of about 20nm was formed.