Abstract No.:	4794
Title:	Understanding element redistribution of molten Mo-shell/Cu-core structured powder particles during in-flight in plasma spraying
Authors:	Chang-Jiu Li / Xi'an Jiaotong University, P.R. China Jia-Jia Tian* / State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xian Jiaotong University, China Xiao-Tao Luo/ State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xian Jiaotong University, China Guan-Jun Yang/ State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xian Jiaotong University, China Cheng-Xin Li/ State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xian Jiaotong University, China
Abstract:	Interface bonding within plasma sprayed metallic and alloy coatings dominates the overall performance of coatings. Previous studies revealed that through shell-core structured powder designing with high melting point Mo cladding around low melting point NiCr alloy, improved cohesion and adhesion were obtained through enhanced metallurgical bonding consequently. In this study, in order to clarify the element distribution of molten Mo-clad metal particles created by plasma heating, a shell-core structured powder system designing with high melting point Mo cladding around spherical copper, in which the two elements are not mutual soluble, is prepared to study the flow characteristics of the shell-core particles during in-flight heating process. In-flight Mo-clad Cu particles are collected and cross-section of single Mo-Cu splats deposited onto polished Cu substrate are prepared by FIB for microstructure characterization. The morphology of collected particles passing through plasma jet shows that molten Mo segregates towards the one end of the composite droplet. Moreover, from the surface morphology of the Mo-Cu single splats only copper was observed, while the cross-section structure of Cu-Mo splat prepared by FIB revealed that Mo exists underneath of top Cu layer. The results clearly reveal that Mo is segregated surrounding the front of in-flight particles which first impacts the substrate. Accordingly, impact-induced substrate melting would take place attributing to the intimate contact of Mo to substrate during impact.

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