Abstract No.:
5276

 Scheduled at:
Friday, June 09, 2017, Hall 27 9:00 AM
Metal Coatings


 Title:
The effect of Mo substrate oxidation on splat formation

 Authors:
Chang-Jiu Li / Xi'an Jiaotong University, P.R. China
Jun Wang* / Xi'an Jiaotong University, China
Cheng-Xin Li/ Xi'an Jiaotong University,
Guan-Jun Yang/ Xi'an Jiaotong University,

 Abstract:
Disk splats are usually observed when the deposition temperature exceeds the transition temperature, whereas the high deposition temperature promotes the surface oxidation. In present study, single molybdenum splats were formed on polished molybdenum substrates with different preheating processes to clarify the effect of surface oxidation on the splat formation. Three different preheating processes included heating the substrate to 350 oC, heating the substrate to 550 oC, and cooling the substrate from 550 oC to 350 oC, which were performed in argon atmosphere. The cross sections of splats were prepared by focus-ion-beam (FIB), and then characterized by SEM. Results showed that nearly disc-shape splats were observed on the molybdenum substrate at 350 oC, with small fingers in the periphery. Perfect disc-shape splats were found at 550 oC. However, the annular rim separated with the central zone if the substrate was preheated at 550 oC and then cooled to 350 oC. The peeling off of splats by carbon tape and the cross sections prepared by FIB showed that if the substrate was ever preheated to 550 oC, no effective bonding formed in the interface between the splat and substrate, indicating that the oxidation resulting from the preheating process had a significant influence on the interface bonding formation. The compositions of preheated substrates were examined by XPS. A novel approach was proposed to eliminate the surface oxide to improve the interface contact during thermal spraying.

<= go back