Browsing by Subject "air plasma spray"

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    The 1st International Joint Mini-Symposium on Advanced Coatings between Indiana University-Purdue University Indianapolis and Changwon National University: Preface
    (2014) Zhang, Jing; Jung, Yeon-Gil
    The 1st international joint mini-symposium on advanced coatings between Indiana University-Purdue University Indianapolis (IUPUI) and Changwon National University (CNU) was held on March 18-20, 2014 in Indianapolis, Indiana, USA. Research papers presented in the symposium are included in this proceeding. The symposium covered recent development in advanced coatings and related functional materials. The symposium offered the students and researchers from both universities a valuable opportunity to share a wide spectrum of new knowledge of advanced coatings and related functional materials. The research topics presented in the symposium included thermal barrier coatings, bio-related coatings, nano-materials and materials for energy conversion. The symposium enabled face-to-face discussions and developed genuine friendship, which promoted international collaboration and exchange program for researcher as well as students to carry out science work together. J.Z. would like to thank the support provided by the US Department of Energy (Grant No. DE-FE0008868, program manager Richard Dunst) and International Development Fund by the IUPUI Office of Vice Chancellor for Research. Y.G.J. acknowledges the support provided by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (MSIP) (No. 2011-0030058) and the Human Resources Development Program (No. 20134030200220) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean Government Ministry of Trade, Industry and Energy.
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    Microstructural non-uniformity and mechanical property of air plasma-sprayed dense lanthanum zirconate thermal barrier coating
    (2014) Zhang, Jing; Guo, Xingye; Jung, Yeon-Gil; Li, Li; Knapp, James
    Lanthanum zirconate is a promising thermal barrier coating material. In this work, imaging technique was used to characterize the microstructural non-uniformity of the coating. The imaging analyses revealed that, along the thickness of the coating, the cracks were primarily horizontal in the top and middle regions, while vertical cracks became dominant in the bottom region. The calculated porosities showed a non-uniformity (4.8%, 5.3%, and 5.5% in the top, middle, and bottom regions, respectively). They were lower than the experimentally measured one, 7.53%, using the Archimedes method. This is because imaging analysis does not take internal porosity into account. Additionally, the measured Vickers hardness was 5.51±0.25 GPa, nanoindentation hardness was 8.8±2.1 GPa, and Young's modulus was 156.00±10.03 GPa.
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    Microstructure evolution and thermal durability with coating thickness in APS thermal barrier coatings
    (2014) Lu, Z; Myoung, S W; Kim, E H; Lee, J H; Jung, Y G
    The effects of the coating thickness on the delamination or fracture behavior of thermal barrier coatings (TBCs) were investigated through the cyclic furnace thermal fatigue (CFTF) and thermal shock (TS) tests. The TBCs were prepared using a NiCrAlY bond coat and an yttria-stabilized zirconia top coat, which were formed using the air plasma spray (APS) process. The thicknesses of the top coat were 200 and 400 μm, and those of the bond coat were 100 and 200 μm. TBC samples with a thickness ratio of 2:1 in the top and bond coats were employed in the CFTF and TS tests. After CFTF for 1429 cycles, the interface microstructure of the relatively thick TBC was in a sound condition without any cracking or delamination; however, the relatively thin TBC was delaminated near the interface between the top and bond coats after 721 cycles. In the TS, the TBCs were fully delaminated (> 50%) after 140 and 194 cycles for thicknesses of 200 and 400 μm in the top coat, respectively. These observations allow us to control the thickness of TBC prepared using the APS process, and the thicker TBC is more efficient in improving thermal durability in the cyclic thermal exposure and thermal shock environments.