• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.62-73
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• 1998

The aim of this work was to investigate the effects of pigment composition on the calendering response and structure of the coated paper. Calendering response of the coated paper was determined from the gloss values of the uncalendered and calendered coated papers, and the relationship between gloss and coating structure was discussed. The surface and cross section of the coating layer was observed using a scanning electron microscope to examine the coating structure. Coating layers were hardened in epoxy resin and polished with carbimet paper disc for preparing SEM samples. Maximum calendering response was obtained for the coated paper prepared from 80pph of clay and 20pph of ground calcium carbonate (GCC) as pigments. Photomicrographs of the surface and cross section of the coating layer show that clay tends to form dense coating structure, while GCC tends to form bulky coating layer.

• Tribology and Lubricants
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• v.27 no.1
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• pp.1-6
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• 2011

The possibility of Cu-Al-Ni intermetallic coating on the mild steel through the combustion synthesis has been investigated. In particular, the effect of the ball milling energy on the microstructure of the coating layer was examined to obtain the best coating condition. Experimental results show that Cu-Al-Ni powder compact was explosively synthesized and successfully coated with the steel matrix. It was revealed that the formation of $Cu_9Al_4$ intermetallic decreased with increase in the ball milling energy. This result supports that the high energy ball milling would be effective for obtaining the most suitable microstructure for Cu-Al-Ni coating layer. However, the excessive ball milling energy seems to decrease the bonding strength between the coating layer and the matrix.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1281-1282
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• 2007

Effect of tension coating on reducing iron losses of thin grain-oriented 3% Si-Fe steel sheets was investigated. Conventional grain-oriented electrical steel sheets have a forsterite coating layer and a tension coating layer in order to apply tensile stress to the rolling direction of the sheets. However the proposed coating method in this paper is to form only a tension coating layer on the both surfaces of the sheets. Iron losses with the tension coating were reduced by 8% under the condition of 1.7 T and 60 Hz. Consequently the proposed tension coating is applicable to $80{\mu}m$-thick 3% Si-Fe steel sheets.

• Corrosion Science and Technology
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• v.20 no.4
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• pp.175-182
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• 2021

Magnesium alloy is limited in the industrial field because its standard electrode potential is -2.363 V vs. NHE (Normal Hydrogen Electrode) at 25 ℃. This high electrochemical activity causes magnesium to quickly corrode with oxygen in air; chemical conversion coating prevents corrosion but causes surface defects like cracks and pores. We have examined the anti-corrosion effect of sol-gel coating sealed on the defected conversion coating layer. Sol-gel coatings produced higher voltage current and smaller pore than the chemical conversion coating layer. The conversion coating on magnesium alloy AZ31 was prepared using phosphate-permanganate solution. The sol-gel coating was designed using trimethoxymethylsilane (MTMS) and (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) as precursors, and aluminum acetylacetonate as a ring-opening agent. The thermal shock resistance was tested by exposing specimens at 140 ℃ in a convection oven; the results showed changes in the magnesium alloy AZ31 surface, such as oxidization and cracking. Scanning electron microscope (FE-SEM) analysis confirmed a sealed sol-gel coating layer on magnesium alloy AZ31. Electrochemical impedance spectroscopy (EIS) measured the differences in corrosion protection properties by sol-gel and conversion coatings in 0.35 wt% NaCl solution, and the potentiodynamic polarization test and confirmed conversion coating with the sol-gel coating show significantly improved resistance by crack sealing.

• Journal of Powder Materials
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• v.21 no.3
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• pp.229-234
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• 2014

This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and a mixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, the Cu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of $35.4{\mu}m$. Through the utilization of a warm spray process, a CIG-based composite coating layer of $180{\mu}m$ thickness could be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layer underwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, an annealing heat treatment was conducted at temperatures of $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ for 1 hour each. The microstructure analysis identified ${\alpha}$-Cu, $Cu_4In$ and $Cu_3Ga$ phases in the early mixed powder, while $Cu_4In$ disappeared, and additional $Cu_9In_4$ and $Cu_9Ga_4$ phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatment reduced from 0.75% (warm sprayed coating layer) to 0.6% (after $600^{\circ}C/1hr$. heat treatment), and hardness reduced from 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.

• Membrane Journal
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• v.25 no.6
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• pp.538-546
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• 2015

In this study, composite membrane is prepared by Layer-by-Layer method using hydrophobic polymer as a coating material on the polysulfone support. The existence of coating layer on the surface and cross section was confirmed by the scanning electronic microscopy. The flux and rejection of the resulting membranes were characterized using 100 ppm NaCl feed solution. PVSA, PEI, PAA, PSSA, PSSA_MA were used as a coating polymer in this study. The composite membrane prepared by using 8,000 ppm PAA solution (Ion strength = 0.35, Coating time = 3 min) and 10,000 ppm PEI solution (Coating time = 4 min). As a result, PAA-PEI composite membrane showed flux of 101 LMH and salt rejection of 66.7%. The composite membrane showed the comparable performance as good as NE 4040-70 (Flux = 30 LMH, Rejection = 40~70%) model produced by Toray Chemical co.

• Journal of Powder Materials
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• v.24 no.1
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• pp.46-52
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• 2017

Fecralloy coating layer with large surface area is suitable for use as a filter media for efficient removal of hot gaseous pollutants exhausted from combustion processes. For uniform preparation of a Fecralloy coating layer with large surface area and strong adhesion to substrate, electrospray coating and thermal treatment processes are experimentally optimized in this study. A nano-colloidal solution with 0.05 wt% Fecralloy nanoparticles is successfully prepared. Optimized electrospraying conditions are experimentally discovered to prepare a uniform coating layer of Fecralloy nano-colloidal solution on a substrate. Drying the electrospray coated Fecralloy nano-colloidal solution layer at $120^{\circ}C$ and subsequent heating at $600^{\circ}C$ are the best post-treatment for enhancing the adhesion force and surface roughness of the Fecralloy coating layer on a substrate. An electrospray coating system, consisting of several multi-groove nozzles, is also experimentally confirmed as a reasonable device for uniform coating of Fecralloy nano-colloid on a large area substrate.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.161-168
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• 2001

A Thermal Barrier Coating (TBC) can play an important role in protecting parts from harmful environments at high temperatures such as oxidation, corrosion, and wear in order to improve the efficiency of aircraft engines by lowering the surface temperature of the turbine blade. The TBC can increase the life span of the product and improve the operating properties. Therefore, in this study the mechanical and thermal properties of the TBC such as oxidation, fatigue and shock at high temperatures were evaluated. A samples of a bond coat (CoNiCrAlY) produced by the High Velocity Oxygen Fuel (HVOF) and Low Pressure Plasma Spray (LPPS) method were used. The thickness of the HVOF coating layer was approximately $450\mu\textrm{m}$ to 500$\mu\textrm{m}$ and the hardness number of the coating layer was between 350Hv and 400Hv. The thickness of the LPPS coating was about 350$\mu\textrm{m}$ to 400$\mu\textrm{m}$ and the hardness number of the coating was about 370Hv to 420Hv. The X-ray diffraction analysis showed that CoNiCrAlY coating layer of the HVOF and LPPS was composed of the $\beta$and ${\gamma}$phase. After the high temperature oxidation test, the oxide scale with about l0$\mu\textrm{m}$ to 20$\mu\textrm{m}$ thickness appeared at the coating surface on the Al-depleted zone was observed under the oxide scale layer.

• Corrosion Science and Technology
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• v.14 no.4
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• pp.161-165
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• 2015

This paper presents an analysis of thermal stress induced along the interface between a polymeric coating layer and a steel substrate as a result of uniform temperature change. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The numerical results exhibit relaxation of interface stresses and large stress gradients, which are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the polymeric coating layer, local cracking or delamination can occur at the interface corner.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.72-76
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• 2005

Friction surfacing of STS304 consumable rod on S45C substrate was investigated by microstructural observation and mechanical tests. STS304 layer formed a strongly-bonded thick layer under a wide range of surfacing conditions. The highest coating eefficiency was obtained in the condition of 1000rpm-2.5mm/sec-2.5mm/sec. The hardness distribution showed the peak value in the boundary layer and as the consumable rotation speed increased, the boundary layer also hardness increasing. As the consumable rotation speed and the traveling speed increased, the coating efficiency tended to decrease. On the other hand, as the feeding speed increased, the coating efficiency appeared to be increased. The new Fe-Cr-Ni alloy layer is showed in the interface layer on $5\~15{\mu}m$ width. After friction surfacing, corrosion resistance of STS 304 surfacing layers were equaled to that of STS304 consumable rod.