• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.481-486
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• 2014

Environmental barrier coatings (EBCs) are used to protect SiC-based ceramics or composites from oxidation and corrosion due to reaction with oxygen and water vapour at high temperatures above $1000^{\circ}C$. Mullite ceramics have been studied for environmental barrier coatings for Si-based ceramics. More recently, rare earth silicate ceramics have been identified as more water vapour-resistant materials than mullite for environmental barrier coatings. In this study, we fabricate mullite and yttrium silicate ceramics by an atmospheric plasma spray coating method using spherical granules fabricated by spray drying. As a result, EBCs with thicknesses in the range of $200-300{\mu}m$ are successfully fabricated without any macroscopic cracks or interfacial delamination. Phase and microstructure analysis are conducted, and the basic mechanical properties, such as hardness and indentation load-displacement curves are evaluated.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1634-1637
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• 2008

We will discuss encapsulation of OLEDs on both flexible and rigid glass substrates. Accelerated testing at 6CC/90RH and 85C/85RH is compared and acceleration factors for OLED and Calcium test samples are discussed.We have tested the stability and performance of our barrier coating to much higher temperatures: up to 140 C. Water Vapor Transmission rates at temperatures from 60 to 140 C are presented. Rates and methods for low cost manufacturing on a large scale are analysed.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.589-593
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• 2005

It is well known that proper encapsulation is crucial for the lifetime of organic light emitting diode (OLED) displays. With the development of increasingly better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation measurement method that uses tritium-containing water (HTO) as a tracer material. The theoretical detection limit of this direct method is $2.4{\times}10^{-8}g/(m^2day)$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1722-1725
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• 2007

We will discuss and compare the different ways to manufacture high performance Barix coated barrier films as a substrate for displays: R2R vs Batch. It will be shown that the barrier performance of the Barix coating on plastic can be as good as on glass substrates. More then 1000 hrs of testing at 60C/90RH can be passed without degradation of Ca samples

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.376-382
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• 2022

Yb₂Si₂O₇ has a coefficient of thermal expansion similar to that of the base material of SiC and has excellent corrosion resistance in a high-temperature oxidizing atmosphere including water vapor, so it is being studied as one of the materials for environmental barrier coatings (EBCs). In this study, Yb₂Si₂O₇ powder granule is deposited using atmospheric plasma spraying (APS) with different Ar/He ratios. Phase formation and microstructural characteristics are investigated with the coated specimens. In the coating layer, the crystallinity decreased, and the amorphous content increased from an increase in the ratio of Ar. In addition, the various types of particles involved by local volatilization of Si according to the Ar/He ratios were identified.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1699-1702
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• 2007

We will discuss encapsulation of OLEDs on both flexible and rigid glass substrates. Accelerated testing at 6CC/90RH and 85C/85RH is compared and acceleration factors for OLED and Calcium test samples are discussed.We have tested the stability and performance of our barrier coating to much higher temperatures: up to 140 C. Water Vapor Transmission rates at temperatures from 60 to 140 C are presented. Rates and methods for low cost manufacturing on a large scale are analysed

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.806-809
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• 2009

Epoxy functionalized organic-inorganic hybrid materials (hybrimers) were synthesized by sol-gel reaction for application in OLED barrier coating. By using the calcium degradation method, the oxygen transition rate (OTR) and water vapor transition rate (WVTR) measured so far is $10^{-2}cc/m^2$-day for oxygen and $10^{-1}g/m^2$-day for water molecules with single hybrimer coating film, respectively. Encapsulated OLED devices have life time of 14hrs of a single hybrimer barrier coating and 29hrs of hybrimer/inorganic double barrier coatings at $25^{\circ}C$ and 60% relative humidity.

• Journal of the Korean institute of surface engineering
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• v.54 no.6
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• pp.331-339
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• 2021

Environmental barrier coatings(EBCs) are applied to the SiC/SiC ceramic matrix composites(CMCs) in order to protect CMCs from being corroded with water vapor by combustion gas in gas turbine engines. Ytterbium silicates, such as ytterbium monosilicate and ytterbium disilicate, are ones of the candidate materials for EBCs due to their excellent resistance to water vapor corrosion as well as thermal-expansion match with SiC. In this study, ytterbium silicates are fabricated with 2-step solid-state synthesis targeting ytterbium disilicate. After synthesizing ytterbium monosilicate, the mixtures of ytterbium monosilicate and SiO₂ are heat-treated and densified by using pressureless sintering or hot pressing with a variety of heating conditions. The phase formation, thermal expansion, and oxidation behavior are examined with fabricated specimens. The final densified bodies are found to be composites between ytterbium monosilicate and ytterbium disilicate with different ratios, which results in 4.43 to 6.72×10^-6/K range of coefficients of thermal expansion. The probability of these ytterbium silicates for EBC applications is also discussed.

• Corrosion Science and Technology
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• v.8 no.6
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• pp.223-226
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• 2009

Polymer coatings are commonly applied to metal substrates to prevent corrosion in aggressive environments such as high humidity and under salt water. Once the polymer coating has been breached, for example due to cracking or scratches, it loses its effectiveness, and corrosion can rapidly propagate across the substrate. The self-healing system we will describe prevents corrosion by healing the damage through a healing reaction triggered by the actual damage event. This self-healing coating solution can be easily applied to most substrate materials, and our dual-capsule healing system provides a general approach to be compatible with most common polymer matrices. Specifically, we expect an excellent anti-corrosion property of the self-healing coatings in damaged parts coated on galvanized metal substrates.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.443-450
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• 2023

SiC/SiC_f CMC is vulnerable to water vapor corrosion at a high temperature of 1500℃. So, EBC (Environmental Barrier Coating) materials are required to protect Si-based CMCs. Ytterbium silicates are reported to have coefficient of thermal expansion (CTE) similar to that of the base material, such as SiC/SiC_f CMC. When the EBC are materials exposed to high temperature environment, the interface between ytterbium silicates and SiC/SiC_f CMC is not separated, and the coating purpose can be safely achieved. For the perspective of EBC applications, thermally grown oxide (TGO) layer with different CTE is formed by the reaction with water vapor in EBC, which leads to a decrease in life time. In this study, we prepare two types of ytterbium silicates to observe the corrosion behavior during the expose to high temperature and water vapor. In order to observe this behavior, the steam-jet furnace is prepared. In addition, phase formation of these ytterbium silicates is analyzed with microstructures by the before/after steam-jet evaluation at 1500℃ for 100 h.