Browsing by Author "Gulhane, Abhilash"

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    Experimental and Modeling Studies of Bond Coat Species Effect on Microstructure Evolution in EB-PVD Thermal Barrier Coatings in Cyclic Thermal Environments
    (MDPI, 2019) Lu, Zhe; Lyu, Guanlin; Gulhane, Abhilash; Park, Hyeon-Myeong; Kim, Jun Seong; Jung, Yeon-Gil; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and Technology
    In this work, the effects of bond coat species on the thermal barrier coating (TBC) microstructure are investigated under thermal cyclic conditions. The TBC samples are prepared by electron beam-physical vapor deposition with two species of bond coats prepared by either air-plasma spray (APS) or high-velocity oxygen fuel (HVOF) methods. The TBC samples are evaluated in a variety of thermal cyclic conditions, including flame thermal fatigue (FTF), cyclic furnace thermal fatigue (CFTF), and thermal shock (TS) tests. In FTF test, the interface microstructures of TBC samples show a sound condition without any delamination or cracking. In CFTF and TS tests, the TBCs with the HVOF bond coat demonstrate better thermal durability than that by APS. In parallel with the experiments, a finite element (FE) model is developed. Using a transient thermal analysis, the high-temperature creep-fatigue behavior of the TBC samples is simulated similar to the conditions used in CFTF test. The FE simulation predicts a lower equivalent stress at the interface between the top coat and bond coat in bond coat prepared using HVOF compared with APS, suggesting a longer cyclic life of the coating with the HVOF bond coat, which is consistent with the experimental observation.
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    Modeling of Temperature Swing Effect in Silica Reinforced Porous Anodized Aluminum Based Thermal Barrier Coating
    (SAE International, 2021) Gulhane, Abhilash; Zhang, Jian; Yang, Xuehui; Lu, Zhe; Park, Hye-Yeong; Jung, Yeon-Gil; Li, Yafeng; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and Technology
    This paper presents a finite element (FE) based model to simulate the temperature swing phenomenon of Silica Reinforced Porous Anodized Aluminum (SiRPA) thermal barrier coatings (TBCs). A realistic 3D SiRPA coating microstructure is constructed, based on the morphology of an experimentally grown coating structure, and the known relationship of geometry and anodization parameters. The coatings’ thermophysical properties are first computed using the FE model. The predicted thermal conductivity, thermal diffusivity, and bulk density are compared well with the experimental values. Also, transient thermal analysis is conducted to model the temperature swing effect of the coating by comparing the temperature fluctuation of SiRPA coating with conventional Yttria Stabilized Zirconia (YSZ) based TBCs. With the predicted thermophysical properties, the model is capable to predict the “temperature swing” effect of SiRPA by a transient thermal analysis. Temperature fluctuation of SiRPA is found greater compared to YSZ coating, suggesting its applicability in internal combustion engines. The porosity-dependent thermal conductivity of SiRPA coating is numerically derived. The thermal conductivity decreases linearly with increasing total porosity. The modeling data illustrate that the SiRPA coating shows a higher fluctuation compared to YSZ based TBCs, suggesting its applicability in internal combustion engines.