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4674 |
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Wednesday, May 11, 2016, Room 3E 2:20 PM Suspension Spraying II |
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Microstructure formed by axial suspension plasma spraying: From YSZ splat to coating |
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Dachuan Li* / Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Jingwei Feng / Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Huayu Zhao/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Chengguang Liu/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Linlin Zhang/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Fang Shao/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Yuexing Zhao/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Shunyan Tao/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China |
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In the current work, yttria stabilized zirconia splats and coatings were deposited onto superalloy substrates with different temperatures using axial suspension plasma spraying (ASPS). The microstructure of splats and coatings were characterized by scanning and transmission electron microscopes. As the substrate was heated from room temperature to 300, the morphologies of ASPS splats changed rapidly. However, when the substrate temperature further increased, the variation of morphology was less conspicuous. Integrated ASPS splats were peeled-off from the substrate using a plating and etching approach for TEM examination. The observation on morphological and crystallographic features of splats revealed that the cooling rate during impacting and spreading of an ASPS droplet might be lower than that of a conventional APS droplet. Based on the characteristics of ASPS splats, a possible mechanism consisting shadowing effect and flash sintering was proposed to explain the so-called cauliflower microstructure. In addition, as-sprayed ASPS coating was also examined by X-ray diffraction and nano-indenter to determine its phase composition and microstructure, respectively. Keywords: axial suspension plasma spraying; yttria stabilized zirconia; splat; microstructure; high resolution transmission electron microscope. |