• Journal of the Korean Applied Science and Technology
• /
• v.28 no.2
• /
• pp.240-246
• /
• 2011

UV-Curable hybrid coatings were synthesized to improve the surface properties of plastic film. Organic-inorganic coating solutions were prepared by the sol-gel method using urethane-acrylate oligomer, acrylate monomer, photo initiator and tetraethoxysilane (TEOS). Methacryloyloxypropyltrimethoxysilane(MPTMS) was used as a silane coupling agent to improve chemical interaction between inorganic phases and UV curable acrylate. In this study, the surface hardness and adhesive properties were improved with the use of inorganic component. The experimental results showed that UV-Curable hybrid films containing aliphatic urethane oligomer, hexanedioldiacrylate, trimethylolpropanetriacrylate, hydroxy dimethyl acetophenone exhibited good surface properties. Also, the optimum curing conditions were investigated.

• Journal of the Korean institute of surface engineering
• /
• v.31 no.2
• /
• pp.91-100
• /
• 1998

NiCrAlY/YSZ(8wt%$Y_2O_3-ZrO_2$) functionally graded thermal barrier coating (FGC) layers on a Co-base superalloy (HAYNESS 188) substrate were fabstrate were fabicated using Ar shielded single torch air plasma spraying method. Functional grading with the stepwise compositional change throughout layer thickness. Microstructural observation trvealed a successful fabrication of NiCrAlY/YSZ FGC. From the results of the curvature measurement, adhesive strength measurement and thermal shock test for the FGC, it was concluded that the optimum conditions of functionally graded coating layer thinkness and compositional pattern exit to enhance the properties of FGC, which is closely related to the internal residual stess distribution witin it.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.3 no.1
• /
• pp.75-84
• /
• 1993

Copper coating on graphite powders was carried out by cementation process from copper sulfate solution. Effects of operation variables such as copper ion concentration, stirring speed, reaction time and temperature were investigated to obtain optimum conditions for continuous and uniform copper coating on graphite powders. The activation energy of the copper coating process was found to be 3. 59kcal/mole.

• Textile Coloration and Finishing
• /
• v.17 no.6 s.85
• /
• pp.20-26
• /
• 2005

For developing digital printing textiles, special pretreatment processes are necessary. These processes include developing formulation of coating agent and coating processes. The pretreatment were investigated with the variation concentration of anti-migration agent, fixation chemical etc.. The printing qualities according to pretreatment conditions were studied with color yield, printed capital letter sharpness and washing fastness. It was observed that the concentration of anti-migration agent, fixation agent(alkali) was closely related to printing qualities. For developing industrial technology of cellulosic digital printing textiles, optimum viscosity of pretreatment coating formulation is very important factor.

• Journal of the Microelectronics and Packaging Society
• /
• v.19 no.4
• /
• pp.65-69
• /
• 2012

Composite coating can be manufactured during the electroplating with the bath containing a suspension of particles: ceramic, polymer, nanopowders. Improvement of hardness, wear resistance, corrosion resistance and lubrication properties are well-known advantage of composite coating. In this study, nano $TiO_2$ powder dispersed Ni composite plating was investigated. The improvement of surface hardness and photo decomposition effects can be expected in this coating. Zeta potential was measured with pH. The effect of ultrasonication time and types of ultrasonicator were studied to minimize the agglomeration of $TiO_2$ nanopowders in the electrolyte. Optimum conditions for nano $TiO_2$ dispersed Ni composite coating were $40mA/cm^2$ of current density, pH 3.5, and $50^{\circ}C$. At these conditions, $TiO_2$ nanoparticles contents in the Ni deposit was 15-20 at.%.

• Clean Technology
• /
• v.7 no.1
• /
• pp.65-74
• /
• 2001

Modified dip-coating method 8.3 times shorten in solution volume-coated and 83.3 times in coating time than existing dip-coating method. Coating weight increased nearly 2~3 times. So modified dip-coating method is evaluated that it is economic and has a efficiency. When we make an experiment in coated $LaCoO_3$ on ceramic monolith in modified dip-coating method which use 2 coating applications with relative viscosity $0.006202kg{\cdot}m/sec$, it showed a superior reaction at 88.56mg per ceramic unit gram in NO-CO reaction(optimum coating amount). When we make an experiment in the same size of ceramic filter cell with different conditions 100, 200cell per square inch, the result in low temperature($200^{\circ}C{\sim}350^{\circ}C$), 200cell3 per square inch is 6~23% higher in NO reduction and 11% in CO oxidation than 100cell per square inch. It is because the more the number of cells in the ceramic filter increase, the more catalytic surface area is expanded.

• Journal of Welding and Joining
• /
• v.20 no.2
• /
• pp.109-115
• /
• 2002

In the case of using high temperature by coating ceramic/metal, large stress was produced due to difference of thermal expansion coefficient between those. And then lead to delamination. In order to relaxation of the stress A1$_2$O$_3$/SS316 composite powders with $10wt.%Al_2O_3$ compositional gradient and $10wt.%Al_2O_3$ agglomerated powder were made by spray drying method. These powders were sintered to improve the strength and to be plasma sprayed in order to fabricate the FGC(functionally graded coating). The influence of gun power, working distance and Ar pressure on the microstructure of the coating layer was studied in order to optimize the plasma spray conditions. It was proven that the optimum conditions were 40kw gun power, 5cm working distance and $100ft^3/h$ Ar flow for both powders. FGC with 10 compositional steps was fabricated and the total thickness was 1.3mm. FGC was heat treated at $1100^{\circ}C$for 10hours to evaluate the heat resisting characteristics.

• Tribology and Lubricants
• /
• v.28 no.6
• /
• pp.283-288
• /
• 2012

In this study, a new sliding contact problem involving an elastomeric seal, a spherical particle and a hard coated steel counterface was modeled to investigate the detailed wear mechanisms related to the sealing surface. The model was also used to design the optimum coating conditions. A three-dimensional finite element contact problem was modeled and analyzed using the nonlinear finite element code, MARC. The deformed steel surface and stress distributions are presented for different coating layers and thicknesses. When the coating thickness is relatively small, the entrapped particle produces surface plastic deformations such as groove and torus. In addition, the sealing surface can be damaged by abrasive wear as well as fatigue wear. For a relatively thick and multi-layered coating, on the other hand, surface plastic deformation does not occur, and the amount of abrasive and fatigue wear is reduced. Therefore, the proposed contact model and results can be used in the design of various sealing systems, further intensive studies are required.

• Journal of the Korean institute of surface engineering
• /
• v.26 no.4
• /
• pp.192-202
• /
• 1993

The characteristics of the high-performance ceramic coatings fabricated on the optimum processings con-ditions for the atmospheric plasma spraying are evaluated by various material tests and analyses. The opti-mum processing parameters for the plasma spraying are determined by using the two-level orthogonal arrays of fractional factorial testing method as a statistical approach. Material tests for the coating specimens are carried out to evaluate microstructure, hardness, adhesion strength, and deposition efficiency. The properties of Al2O3-13%TiO2 coating are discussed with regard to the effective processings parameters. The decarburization effects of WC-12%Co coating is examined by XRD analysis in terms of the arc power and the secondary gas species. The hardness of Al2O2-13%TiO2 coating is increased with the arc power and shows the maximum value at around 40 lpm of Ar gas flowrate, which appears to be the most critical parame-ter on the deposition efficiency. For reducing the decarburization of WC-12%Co coating, the injection of inert He gas instead of reactive H2 gas as a secondary gas is more effective than the dropping of arc power to lessen the plasma enthalpy.

• Journal of Welding and Joining
• /
• v.14 no.3
• /
• pp.41-47
• /
• 1996

The spot weldability of coated steels for automobile has been investigated. Coated steels of SPC-Zn DC, SPC Zn-Ni SC, SPC Zn-Ni DC, SPC Zn-Fe DC and OCCS were welded under different conditions of welding current, force and time. Coating thickness at the welded surface was reduced as increased welding current. Tensile shear strength(TSS) and cross tensile strength (CTS) were increased up to expulsion began, then dropped as increased current. Optimum conditions of welding force and time were different, however 200~250kgf and 15~20cycle were optimum for coated SPC (Steel Plate Cold). Weldability lobes were measured for each coated steel and they showed narrow range of working welding current. The organic composite coated steel (OCCS) had the highest current to get $\sqrt5{t}$ nugget size and narrowest working welding current range.