The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Kang N. Lee - One of the best experts on this subject based on the ideXlab platform.

  • Environmental Durability of slurry based mullite gadolinium silicate ebcs on silicon carbide
    Journal of The European Ceramic Society, 2011
    Co-Authors: Sivakumar Ramasamy, Kang N. Lee, Surendra N. Tewari, Ramakrishna T. Bhatt, Dennis S. Fox
    Abstract:

    Abstract Water vapor oxidation and salt corrosion resistances of mullite–gadolinium silicate (Gd2SiO5) Environmental barrier coatings (EBCs) dip coated on α-SiC substrates and sintered to 1430 °C/3 h in air were investigated. The EBC exhibited excellent adherence to the substrate during thermal cycling between 1350 °C and room temperature (RT) for 100 h in a simulated lean combustion environment (90% H2O–balance O2), 11 , 13 , 15 forming ∼10 μm porous silica layer at coating-substrate interface, compared to ∼17 μm for uncoated α-SiC exposed under same conditions. The EBC did not spall after a 24 h 1200 °C exposure in Na2SO4 corrosion environment leading to further coat densification. However, after 48 h salt exposure, the EBC showed severe through-thickness cracks, and cavities and de-lamination at coating-substrate interface. The corrosion gaseous products such as CO2, CO and SO2 trapped under a low viscosity glassy (Na2O·x(SiO2)) liquid phase were formed due to salt vapor reaction with α-SiC substrate created these cavities.

  • Environmental Durability of slurry based mullite–gadolinium silicate EBCs on silicon carbide
    Journal of the European Ceramic Society, 2011
    Co-Authors: Sivakumar Ramasamy, Kang N. Lee, Surendra N. Tewari, Ramakrishna T. Bhatt, Dennis S. Fox
    Abstract:

    Abstract Water vapor oxidation and salt corrosion resistances of mullite–gadolinium silicate (Gd2SiO5) Environmental barrier coatings (EBCs) dip coated on α-SiC substrates and sintered to 1430 °C/3 h in air were investigated. The EBC exhibited excellent adherence to the substrate during thermal cycling between 1350 °C and room temperature (RT) for 100 h in a simulated lean combustion environment (90% H2O–balance O2), 11 , 13 , 15 forming ∼10 μm porous silica layer at coating-substrate interface, compared to ∼17 μm for uncoated α-SiC exposed under same conditions. The EBC did not spall after a 24 h 1200 °C exposure in Na2SO4 corrosion environment leading to further coat densification. However, after 48 h salt exposure, the EBC showed severe through-thickness cracks, and cavities and de-lamination at coating-substrate interface. The corrosion gaseous products such as CO2, CO and SO2 trapped under a low viscosity glassy (Na2O·x(SiO2)) liquid phase were formed due to salt vapor reaction with α-SiC substrate created these cavities.

  • development and Environmental Durability of mullite and mullite ysz dual layer coatings for sic and si3n4 ceramics
    Surface & Coatings Technology, 1996
    Co-Authors: Kang N. Lee, Robert A. Miller
    Abstract:

    Abstract Development of refractory oxide Environmental coatings for SiC and Si 3 N 4 ceramics, interaction with simulated combustion environments, and long-term Durability under thermal cycling in air are discussed. Mullite coating performance data indicate its ability to limit the molten salt corrosion. Two-layer mullite/YSZ coating showed promise as a barrier coating limiting enhanced silica volatilization by water vapor in a simulated lean-burn combustion environment. The mullite/YSZ dual layer coatings showed excellent resistance to cracking and debonding for 1000 h using 2-h thermal cycles in air at 1200–1300°C. A CVD SiC bond coat developed for Si 3 N 4 dramatically enhanced the adherence of mullite coatings. Contamination of silica scale by alkali and alkali earth metal oxides resulted in enhanced oxidation and pore formation which is an issue for the long-term Environmental Durability of these coatings.

  • Development and Environmental Durability of mullite and mullite/YSZ dual layer coatings for SiC and Si3N4 ceramics
    Surface and Coatings Technology, 1996
    Co-Authors: Kang N. Lee, Robert A. Miller
    Abstract:

    Abstract Development of refractory oxide Environmental coatings for SiC and Si 3 N 4 ceramics, interaction with simulated combustion environments, and long-term Durability under thermal cycling in air are discussed. Mullite coating performance data indicate its ability to limit the molten salt corrosion. Two-layer mullite/YSZ coating showed promise as a barrier coating limiting enhanced silica volatilization by water vapor in a simulated lean-burn combustion environment. The mullite/YSZ dual layer coatings showed excellent resistance to cracking and debonding for 1000 h using 2-h thermal cycles in air at 1200–1300°C. A CVD SiC bond coat developed for Si 3 N 4 dramatically enhanced the adherence of mullite coatings. Contamination of silica scale by alkali and alkali earth metal oxides resulted in enhanced oxidation and pore formation which is an issue for the long-term Environmental Durability of these coatings.

Kazuki Yoshimura - One of the best experts on this subject based on the ideXlab platform.

  • Si incorporated diamond-like carbon film-coated electrochromic switchable mirror glass for high Environmental Durability
    Ceramics International, 2013
    Co-Authors: Kazuki Tajima, Masami Ikeyama, Setsuo Nakao, Yasusei Yamada, Kazuki Yoshimura
    Abstract:

    Abstract Electrochromic switchable mirror glass is promising for energy-saving windows because it changes between a reflective and a transparent state when a voltage is applied. In our previous work, we confirmed that the device degraded at high temperatures and high relative humidity using an accelerated degradation test. The degradation was related to the reaction of the moisture in atmosphere with the surface optical switching layer of the Mg–Ni thin film. Therefore, we have developed a device with a Si incorporated diamond-like carbon thin film surface layer to improve the Environmental Durability. When the device was kept in a simulated environment at a constant temperature of 40 °C and a constant relative humidity of 60%, optical and atomic force microscopy showed that the surface did not degrade. Moreover, the surface coating repelled water, which prevented the reaction of the moisture with the Mg–Ni thin film. The optical switching speed from the transparent state to the reflective state of the device was slower than that of the uncoated device because of the fabrication conditions. The result seems to be related to the surface of the Mg–Ni layer which might be damaged by the conditions.

  • Environmental Durability of electrochromic switchable mirror glass at sub-zero temperature
    Solar Energy Materials and Solar Cells, 2012
    Co-Authors: Kazuki Tajima, Yasusei Yamada, Hiromi Hotta, Masahisa Okada, Kazuki Yoshimura
    Abstract:

    Abstract Electrochromic switchable mirrors are expected to be used in energy-saving windows because their optical properties can be changed by application of a voltage. For practical use, the negative impact of Environmental conditions on the optical switching properties of the device should be minimized. In this work, the Durability of an electrochromic device was investigated in a thermostat/humidistat chamber at −5 °C. After devices were stored at sub-zero temperatures, the switching speed and maximum transmittance decreased only slightly with increasing exposure time. In other words, degradation of the device did not significantly occur at sub-zero temperatures. In comparison, the optical switching properties of a device stored at 40 °C and 60% relative humidity severely deteriorated. This deterioration was attributed to the degradation of the surface of the Mg 4 Ni optical switching layer. This layer was affected by the Environmental conditions, and in particular changed from the metallic magnesium state to a non-metallic state. In future work, we will investigate suitable measures for preventing Environmental damage to the device.

Robert A. Miller - One of the best experts on this subject based on the ideXlab platform.

  • development and Environmental Durability of mullite and mullite ysz dual layer coatings for sic and si3n4 ceramics
    Surface & Coatings Technology, 1996
    Co-Authors: Kang N. Lee, Robert A. Miller
    Abstract:

    Abstract Development of refractory oxide Environmental coatings for SiC and Si 3 N 4 ceramics, interaction with simulated combustion environments, and long-term Durability under thermal cycling in air are discussed. Mullite coating performance data indicate its ability to limit the molten salt corrosion. Two-layer mullite/YSZ coating showed promise as a barrier coating limiting enhanced silica volatilization by water vapor in a simulated lean-burn combustion environment. The mullite/YSZ dual layer coatings showed excellent resistance to cracking and debonding for 1000 h using 2-h thermal cycles in air at 1200–1300°C. A CVD SiC bond coat developed for Si 3 N 4 dramatically enhanced the adherence of mullite coatings. Contamination of silica scale by alkali and alkali earth metal oxides resulted in enhanced oxidation and pore formation which is an issue for the long-term Environmental Durability of these coatings.

  • Development and Environmental Durability of mullite and mullite/YSZ dual layer coatings for SiC and Si3N4 ceramics
    Surface and Coatings Technology, 1996
    Co-Authors: Kang N. Lee, Robert A. Miller
    Abstract:

    Abstract Development of refractory oxide Environmental coatings for SiC and Si 3 N 4 ceramics, interaction with simulated combustion environments, and long-term Durability under thermal cycling in air are discussed. Mullite coating performance data indicate its ability to limit the molten salt corrosion. Two-layer mullite/YSZ coating showed promise as a barrier coating limiting enhanced silica volatilization by water vapor in a simulated lean-burn combustion environment. The mullite/YSZ dual layer coatings showed excellent resistance to cracking and debonding for 1000 h using 2-h thermal cycles in air at 1200–1300°C. A CVD SiC bond coat developed for Si 3 N 4 dramatically enhanced the adherence of mullite coatings. Contamination of silica scale by alkali and alkali earth metal oxides resulted in enhanced oxidation and pore formation which is an issue for the long-term Environmental Durability of these coatings.

Dennis S. Fox - One of the best experts on this subject based on the ideXlab platform.

  • Environmental Durability of slurry based mullite gadolinium silicate ebcs on silicon carbide
    Journal of The European Ceramic Society, 2011
    Co-Authors: Sivakumar Ramasamy, Kang N. Lee, Surendra N. Tewari, Ramakrishna T. Bhatt, Dennis S. Fox
    Abstract:

    Abstract Water vapor oxidation and salt corrosion resistances of mullite–gadolinium silicate (Gd2SiO5) Environmental barrier coatings (EBCs) dip coated on α-SiC substrates and sintered to 1430 °C/3 h in air were investigated. The EBC exhibited excellent adherence to the substrate during thermal cycling between 1350 °C and room temperature (RT) for 100 h in a simulated lean combustion environment (90% H2O–balance O2), 11 , 13 , 15 forming ∼10 μm porous silica layer at coating-substrate interface, compared to ∼17 μm for uncoated α-SiC exposed under same conditions. The EBC did not spall after a 24 h 1200 °C exposure in Na2SO4 corrosion environment leading to further coat densification. However, after 48 h salt exposure, the EBC showed severe through-thickness cracks, and cavities and de-lamination at coating-substrate interface. The corrosion gaseous products such as CO2, CO and SO2 trapped under a low viscosity glassy (Na2O·x(SiO2)) liquid phase were formed due to salt vapor reaction with α-SiC substrate created these cavities.

  • Environmental Durability of slurry based mullite–gadolinium silicate EBCs on silicon carbide
    Journal of the European Ceramic Society, 2011
    Co-Authors: Sivakumar Ramasamy, Kang N. Lee, Surendra N. Tewari, Ramakrishna T. Bhatt, Dennis S. Fox
    Abstract:

    Abstract Water vapor oxidation and salt corrosion resistances of mullite–gadolinium silicate (Gd2SiO5) Environmental barrier coatings (EBCs) dip coated on α-SiC substrates and sintered to 1430 °C/3 h in air were investigated. The EBC exhibited excellent adherence to the substrate during thermal cycling between 1350 °C and room temperature (RT) for 100 h in a simulated lean combustion environment (90% H2O–balance O2), 11 , 13 , 15 forming ∼10 μm porous silica layer at coating-substrate interface, compared to ∼17 μm for uncoated α-SiC exposed under same conditions. The EBC did not spall after a 24 h 1200 °C exposure in Na2SO4 corrosion environment leading to further coat densification. However, after 48 h salt exposure, the EBC showed severe through-thickness cracks, and cavities and de-lamination at coating-substrate interface. The corrosion gaseous products such as CO2, CO and SO2 trapped under a low viscosity glassy (Na2O·x(SiO2)) liquid phase were formed due to salt vapor reaction with α-SiC substrate created these cavities.

  • Environmental Durability of ceramics and ceramic composites
    1992
    Co-Authors: Dennis S. Fox
    Abstract:

    An account is given of the current understanding of the Environmental Durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' Environmental Durability. Attention is given to the Environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature Environmental response.

Kazuki Tajima - One of the best experts on this subject based on the ideXlab platform.

  • Si incorporated diamond-like carbon film-coated electrochromic switchable mirror glass for high Environmental Durability
    Ceramics International, 2013
    Co-Authors: Kazuki Tajima, Masami Ikeyama, Setsuo Nakao, Yasusei Yamada, Kazuki Yoshimura
    Abstract:

    Abstract Electrochromic switchable mirror glass is promising for energy-saving windows because it changes between a reflective and a transparent state when a voltage is applied. In our previous work, we confirmed that the device degraded at high temperatures and high relative humidity using an accelerated degradation test. The degradation was related to the reaction of the moisture in atmosphere with the surface optical switching layer of the Mg–Ni thin film. Therefore, we have developed a device with a Si incorporated diamond-like carbon thin film surface layer to improve the Environmental Durability. When the device was kept in a simulated environment at a constant temperature of 40 °C and a constant relative humidity of 60%, optical and atomic force microscopy showed that the surface did not degrade. Moreover, the surface coating repelled water, which prevented the reaction of the moisture with the Mg–Ni thin film. The optical switching speed from the transparent state to the reflective state of the device was slower than that of the uncoated device because of the fabrication conditions. The result seems to be related to the surface of the Mg–Ni layer which might be damaged by the conditions.

  • Environmental Durability of electrochromic switchable mirror glass at sub-zero temperature
    Solar Energy Materials and Solar Cells, 2012
    Co-Authors: Kazuki Tajima, Yasusei Yamada, Hiromi Hotta, Masahisa Okada, Kazuki Yoshimura
    Abstract:

    Abstract Electrochromic switchable mirrors are expected to be used in energy-saving windows because their optical properties can be changed by application of a voltage. For practical use, the negative impact of Environmental conditions on the optical switching properties of the device should be minimized. In this work, the Durability of an electrochromic device was investigated in a thermostat/humidistat chamber at −5 °C. After devices were stored at sub-zero temperatures, the switching speed and maximum transmittance decreased only slightly with increasing exposure time. In other words, degradation of the device did not significantly occur at sub-zero temperatures. In comparison, the optical switching properties of a device stored at 40 °C and 60% relative humidity severely deteriorated. This deterioration was attributed to the degradation of the surface of the Mg 4 Ni optical switching layer. This layer was affected by the Environmental conditions, and in particular changed from the metallic magnesium state to a non-metallic state. In future work, we will investigate suitable measures for preventing Environmental damage to the device.