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6520 |
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Influence of deposition parameters on mechanical and tribological
properties of Stellite-6 coatings obtained by cold gas dynamic spray
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Mario Tului / Centro Sviluppo Materiali S.p.A., Italy Pietro Magarò* / University of Calabria, Italy Angelo Luigi Marino/ CSM SpA, Italy Andrea Di Schino/ University of Perugia, Italy Franco Furgiuele/ University of Calabria, Italy Carmine Maletta/ University of Calabria, Italy Rosanna Pileggi/ CSM SpA, Italy Claudio Testani/ CALEF-ENEA, Italy |
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In this study mechanical and tribological properties of wear resistant Stellite-6 coatings obtained by Cold Gas Dynamic Spray (CGDS) were analyzed. The influence of process parameters, i.e. the gas temperature, gas pressure and in particular scan speed, was investigated whereas a High-Pressure CGDS equipment was used and systematic studies were carried out for a deeper understanding of the effects of all investigated process parameters. Deposition parameters were optimized with the aim of obtaining dense deposits with good interparticle bonding, in fact, the aim of this work is to overcome some technical issues arising in the cold spray deposition of hard anti-wear metallic coatings. The deformation mechanisms involved by the deposition process were analyzed by the particle shape at the boundaries. A particular focus has been put on the substrate temperature, that can be regarded as an indirect process parameter. This latter, in fact, was monitored in-situ during deposition, by infrared thermography (IR). Mechanical properties of the coatings were analyzed at nano-scale by instrumented indentation. Indentation hardness (H) and Young's modulus (E) can be identified as parameters able to give significant information on the inter-particle cohesion strength and the work hardening that the particle undergoes during the impact. Results revealed that the substrate temperature, strongly related to the process parameters plays a fundamental role in the coating formation process. Tribological behavior was evaluated by pin-on-disk tests and the wear mechanisms were discussed in terms of local oxidation and possible pull out phenomena. Also the strain-to-failure ratio (H/E) was evaluated as this latter can be seen as an indicator of the limit of elastic behavior in a surface contact. In conclusion, it was demonstrated that both mechanical and tribological properties of CGDS Stellite-6 coatings are mainly affected by the impact temperature of the particle-substrate system and an effective deposition windows were identified. |