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5166 |
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Friday, June 09, 2017, Hall 27 1:40 PM Plasma Spraying II |
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Influence of Ti particle oxidation during APS process on the microstructure of laser remelted NiTi coatings |
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Yan Wang* / University Bourgogne Franche-Comté, France Jiangwei Liu / Univ. Bourgogne Franche-Comté, UTBM, LERMPS, France Geoffrey Darut/ Univ. Bourgogne Franche-Comté, UTBM, LERMPS, France Thierry Poirier/ Institut de Céramique Française, France Jorge Stella/ Universidad Simón Bolívar, Departamento de Ciencia de los Materiales, Venezuela Hanlin Liao/ Univ. Bourgogne Franche-Comté, UTBM, LERMPS, France Marie-Pierre Planche/ Univ. Bourgogne Franche-Comté, UTBM, LERMPS, France |
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Commercial available Ni and Ti powders were mixed together and deposited on stainless steel by atmospheric plasma spray (APS). Subsequently the as-sprayed coatings were laser remelted with a Nd -YAG pulsed laser source. Cross-sections of as-sprayed and laser-remelted coatings were characterized by scanning electron microscopy (SEM). Prior to SEM observations, the laser remelted coatings were polished and etched by Kroll etchant. Meanwhile, the energy dispersive spectrometer (EDS) was employed to analyze the chemical distribution of the both coatings, as-sprayed and laser remelted. Moreover, the X-ray photoelectron spectroscopy (XPS) was performed to estimate the oxidation of Ti particles in the coating. Phase compositions of the coatings were also characterized by X-ray Diffraction. The results indicated that APS sprayed NiTi coatings presented a dense microstructure with Ni and Ti splats distributed uniformly. Additionally, the as-sprayed coatings exhibited a large quantity of Ti oxides. The Ti oxides were preferentially concentrated on the bottom of laser remolten pool as an equiaxed crystal structure. In contrast, the Ni splats floated on the top. The top zone of Ni splats displayed a columnar crystal structure while its transformation occurs in the intermediate zone related to an equiaxed crystal structure. |