• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.121-126
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• 2009

Stainless steel 316L (STS 316L) is widely used as a material of biopsy needle. However it has a side effect that tissue can be damaged by electrochemical operation between tissue and STS 316L. Many studies have been made on the ceramic coating of biopsy needle to reduce the side effect. In this study, STS 316L was coated with three bioceramics, $Al_2O_3$, $SiO_2$ and $ZrO_2$ using a RF magnetron sputtering method. The effects of ceramic coating on the electrical conductivity and coating strength of ceramic-coated STS 316L were investigated. The results showed that the electrical conductivity of ceramic-coated STS 316L was much lower than that of uncoated STS 316L. The coating strength of $ZrO_2$-coated STS 316L was 30% and 70% higher, respectively than those of $Al_2O_3$-coated STS 316L and $SiO_2_3$-coated STS 316L.

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.1-5
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• 2005

An experimental study was conducted to develop an understanding of failure of ceramic coating when subjected to a thermal cycling. Number of cycles to failure were decreased as the coating thickness and the oxide of bond coat were increased. Using the finite element method, an analysis of stress distribution in ceramic coatings was performed. Radial compressive stress was increased in the top/bond coat interface with increasing coating thickness and oxide of bond coat.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.2
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• pp.178-183
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• 2022

For enhancing the flame-retardant properties of wallpapers, we developed an organic-inorganic hybrid solution with ZrSiO₄ as a functional ceramic powder, coated on non-woven fabric using dip coating, spray coating, and slot-die coating methods. Their flame retardant properties were characterized by a 45° combustion tester, which is manufactured according to the flame-retardant performance standard (KOFEIS 1001 and KS F 2819). In organic-inorganic hybrid solution, with increasing the concentration of acid-catalyst (acetic acid), the precipitation of ZrSiO₄ powders increased, and the flame retardant properties decreased. The highest flame retardant result was obtained for the solution adding 5 wt% acetic acid. The optimization of the coating method and coating number resulted in the most excellent flame-retardant properties being obtained for the non-woven fabric coated for 5 or 7 times by dip coating method, and their flame-retardant properties corresponded to class 2 flame-retardant performance of wallpapers.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.395-402
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• 2015

The suspension plasma spray (SPS) technique has been used to obtain dense $Y_2O_3$ coatings and to overcome the drawbacks of the conventional air plasma spray (APS). SPS uses suspensions containing micrometer or sub-micrometer sized powders dispersed in liquid media. In this study, microstructure developments and mechanical properties have been investigated as functions of particle size of source material and plasma processing parameters such as plasma power and stand-off distance. The microstructure of the coating was found to be highly related to the particle size and the plasma processing parameters, and it was directly reflected in the hardness and the adhesion strength. When fine powder (BET $16.4m^2/g$) was used as a raw material in the suspension, there was, with increasing stand-off distance, a change from a dense structure with a slightly bumpy surface to a porous structure with a cauliflower-like surface. On the other hand, when a coarse powder (BET $2.8m^2/g$) was used, the coating density was lower, with microscopic splats on the surface. Using fine $Y_2O_3$ powders, the coating layer with an optimum short stand-off distance showed a high hardness of approximately 90% of that of sintered $Y_2O_3$ and an adhesion strength several times higher than that of the coating by conventional APS.

• Membrane Journal
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• v.31 no.1
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• pp.80-85
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• 2021

In this study, we developed an evaporation-driven self-assembly coating method for an ceramic intermediate layer on an ultrapermeable ��-Al2O3 support with large pore size of ~1.5 ㎛. The method led to the formation of a ceramic intermediate layer with higher surface homogeneity and less surface roughness than the conventional dip-coating method. A mesoporous ��-Al2O3 layer was deposited on the support to evaluate support quality. A supported ��-Al2O3 membrane was defect-free even without repeated coating. Furthermore, the membrane showed 2.3 times higher nitrogen permeance than one prepared on a macroporous support with pore size range of 100~200 nm, which is widely used for ceramic membrane coating.

• Journal of Welding and Joining
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• v.7 no.2
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• pp.25-34
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• 1989

The purpose of this work is to coat ZrO$_{2}$ - 8Y$_{2}$O$_{3}$ ceramic on the Al cast alloy(AC-8A) by using the plasma spray method. Two types of coatings which were composed of two and three layer coating were examined. Each coating powder was analyzed for shape and size distribution and X-ray diffraction pattern. For the coated layers, microstructural analysis and performance estimation which was composed of static thermal test, thermal cyclic test and thermal shock test were conducted.

• Journal of the Korean institute of surface engineering
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• v.30 no.4
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• pp.285-297
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• 1997

Finned segment, with which are lined inner wall of the turbine combustors, are subject to severe degradation when they are exposed to a hostile environmment at elevated temperature. To protect the finned segment from this environment and to maintain good mechanical properties of components at high temperature, they are preferred to be coated. The most governing factor for the durability of coatings used in the high temperature is the microstructure of coatings; these are splat from, distibution of microcacks, size and distribution of pores, thickness of coating layer, adhesion between coating layer, and oxidation of band coating. In this study, based on the evaluation of the imported finned segment, new finned segment segment was manufactured with optimum plasma spraying parameters, and their properties were examined. Using $ZrO_2(8wt$Y_2O_3)$,/TEX> powder for ceramic coating and 67Ni-22Cr-10Al-0.5Y mixing powder for bond coating, thickness of ceramic and bond coating layer were varied in order to find optimum condition, the results showed that B2T4(bond coating : 100~250$\mu\textrm{m}$, ceramic coating : 250~300$\mu\textrm{m}$) was the best among the specimens tested. Compared to the imported finned segment, B2T4 has better bond strength, hardness, and isothermal and cyclic oxidation resistance.

• Journal of Powder Materials
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• v.20 no.6
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• pp.460-466
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• 2013

4 mol% Yttria-stabilized zirconia (4YSZ) coatings with $200{\mu}m$ thick are fabricated by Electron Beam Physical Vapor Deposition (EB-PVD) for thermal barrier coating (TBC). $150{\mu}m$ of NiCrAlY based bond coat is prepared by conventional APS (Air Plasma Spray) method on the NiCrCoAl alloy substrate before deposition of top coating. 4 mol% YSZ top coating shows typical tetragonal phase and columnar structure due to vapor phase deposition process. The adhesion strength of coating is measured about 40 MPa. There is no delamination or cracking of coatings after thermal cyclic fatigue and shock test at $850^{\circ}C$.

• Journal of Powder Materials
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• v.30 no.5
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• pp.415-423
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• 2023

With the increasing attention to environmental pollution caused by particulate matter globally, the automotive industry has also become increasingly interested in particulate matter, especially particulate matter generated by automobile brake systems. Here, we designed a coating composition and analyzed its mechanical properties to reduce particulate matter generated by brake systems during braking of vehicles. We designed a composition to check the mechanical properties change by adding Cr₃C₂ and YSZ to the WC-Ni-Cr composite composition. Based on the designed composition, coating samples were manufactured, and the coating properties were analyzed by Vickers hardness and ball-on-disk tests. As a result of the experiments, we found that the hardness and friction coefficient of the coating increased as the amount of Cr₃C₂ added decreased. Furthermore, we found that the hardness of the coating layer decreased when YSZ was added at 20vol%, but the friction coefficient was higher than the composition with Cr₃C₂ addition.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.85-85
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• 2013

A ceramic coating material with nano-sized silicon oxide on AISI 4340 steel for a thermal conductor at a high temperature was analyzed to find an optimum coating process. Average surface roughness of the coating layers prepared by dipping process was about $5.26{\mu}m$. Potassium silicate addition as a binder of the coating material tended to improve its hardness. A pencil scratch hardness testing showed that a loading more than 800 g made fragments of the coating layer.