Stellite-6 coatings were deposited onto AISI 304 stainless steel substrate by gas-fueled HVOF spraying, systematically varying the process parameter settings. By operating the HVOF torch with a fuel-rich mixture, dense coatings (<1% porosity) are produced, containing up to â3 vol% oxide inclusions. A substantial amount of a Cr-rich f.c.c. phase is found, mainly produced by quenching of molten lamellae, and distinct from the equilibrium, Co-based f.c.c. solid solution retained in unmelted particles. These coatings exhibit pseudo-passive behavior and survive 5 cycles (100 h) of the Corrodkote test (ASTM B380-97) with no substrate corrosion. Coatings obtained from oxygen-rich mixtures, on the other hand, contain fewer oxide inclusions but also greater porosity, and do not protect the substrate against corrosion. The wear behavior of the coatings is less influenced by deposition conditions. In ball-on-disk dry sliding tests, all coatings exhibit wear rates of 2â3 à 10â5mm3/(N·m), higher than those reported for bulk or clad Stellite, because of interlamellar delamination. Strain-induced, âmartensiticâ phase transformation from the f.c.c. structure to a h.c.p. one is observed over a 1â2 μm depth below the contact surface. Additional tribo-oxidation is onset when frictional heat dissipation has heated the wear debris enough to trigger its reaction with the environment. Correspondingly, a transition to a regime of higher friction occurs (from â0.6 to â0.8). At 400 °C, lamellar delamination is suppressed but wear rates rise to 5â8 à 10â5mm3/(N·m) because of abrasive and adhesive wear. At 800 °C, a dense âglazeâ tribofilm is formed by sintered debris particles, firmly bonded to a thermally grown oxide scale on the underlying metal surface. The âglazeâ protects the coating, lowering the wear rate to â1 à 10â5mm3/(N·m) and the friction coefficient to <0.45. Under high-stress particle abrasion conditions, wear rates of â1 à 10â3mm3/(N·m) are found.
Properties of HVOF-sprayed Stellite-6 coatings / Sassatelli, Paolo; Bolelli, Giovanni; Lassinantti Gualtieri, Magdalena; Heinonen, Esa; Honkanen, Mari; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo; Vippola, Minnamari. - In: SURFACE & COATINGS TECHNOLOGY. - ISSN 0257-8972. - 338(2018), pp. 45-62.
Data di pubblicazione: | 2018 |
Titolo: | Properties of HVOF-sprayed Stellite-6 coatings |
Autore/i: | Sassatelli, Paolo; Bolelli, Giovanni; Lassinantti Gualtieri, Magdalena; Heinonen, Esa; Honkanen, Mari; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo; Vippola, Minnamari |
Autore/i UNIMORE: | |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1016/j.surfcoat.2018.01.078 |
Rivista: | |
Volume: | 338 |
Pagina iniziale: | 45 |
Pagina finale: | 62 |
Codice identificativo ISI: | WOS:000427340700006 |
Codice identificativo Scopus: | 2-s2.0-85041473768 |
Citazione: | Properties of HVOF-sprayed Stellite-6 coatings / Sassatelli, Paolo; Bolelli, Giovanni; Lassinantti Gualtieri, Magdalena; Heinonen, Esa; Honkanen, Mari; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo; Vippola, Minnamari. - In: SURFACE & COATINGS TECHNOLOGY. - ISSN 0257-8972. - 338(2018), pp. 45-62. |
Tipologia | Articolo su rivista |
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