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5488 |
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Friday, June 09, 2017, Hall 26 9:00 AM Characterization & Testing Methods II |
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Effect of HVOF thermal spray parameters on the deposition of NiCoCrAlYTa bond coats |
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Alma Gabriela Mora García* / Centro de Investigación y de Estudios Avanzados del Instituto Politecnico National, Mexico Haidee Ruiz Luna/ Conacyt - Universidad Autónoma de Zacatecas, Mexico Carlos Agustin Poblano Salas/ Centro de Tecnología Avanzada, Mexico Uwe Glatzel/ Bayreuth University, Germany Luis Gerardo Trapaga Martinez/ Centro de Investigación y de Estudios Avanzados del I.P.N. / Centro de Tecnología Avanzada, Mexico Juan Muñoz Saldaña/ Centro de Investigación y de Estudios Avanzados del I.P.N., Mexico |
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Preparation of high quality NiCoCrAlY coatings by thermal spray deposition has attracted the attention of scientific community in the last decade seeking to high dense metallic coarse coatings with lower oxide and porosity contents. The final coating quality depends on the spray technique and processing parameters. High-velocity oxygen-fuel (HVOF) is a good candidate due to the high kinetic energy and low temperature reached by the in-flight particles obtained by controlling process parameters during the coating deposition. However, due to the complexity of the HVOF process approaches based on design of experiments (DoE) for a comprehensive analysis of a window of parameters are required. The present study is concerned with the optimization of the deposition of NiCoCrAlYTa coatings by HVOF using DoE. Plume diagnostics are used to characterize velocity and temperature of the in-flight particles in the HVOF deposition under a combination of deposition parameters varying stand-off distance (SOD), powder feed rate (PFR), and fuel-oxygen ratio (F/O) in the fuel-rich flame. First order process maps were constructed to optimize the coating properties based on a parameter-response feedback procedure. Analysis of variance helped to understand the influence of each parameter on the in-flight particles and coatings characteristics. The in-flight particles velocity decreases from 700 to 400 m/s as the SOD is increased. Moreover, the temperature increases from 2150 to 2250 ºC as the F/O decreases. The SOD and PFR have a significant effect on the coatings thickness as well as on their deposition efficiency, increasing from 200 to 300 m, and from 68 to 70 %, respectively. On the other hand, porosity and internal oxidation are affected by the chemistry of the flame and the SOD. As the F/O increases, the temperature of the in-flight particles is minimized as well as their total oxidation. Moreover, as the SOD decreases, the in-flight particles are exposed shorter time in the plume preventing their oxidation during the flight. |