NiCrAlY layers containing different amounts of Al2O3 (0, 3, 6, 12, 18 wt.%) were deposited onto stainless steel substrates by a “hybrid” plasma spray process whereby the NiCrAlY powder was fed in dry form whilst fine Al2O3 powder, dispersed in ethanol, was injected through a suspension feeding system. The Al2O3 reinforcement, consisting of fine, rounded particles interspersed within larger NiCrAlY lamellae, only causes marginal changes in hardness, due to the limited particles-matrix cohesion. Nonetheless, at room temperature, ball-on-disk dry sliding wear rates against sintered Al2O3 counterparts decrease from ≈5⁎10−4 mm3/(Nm) for pure NiCrAlY to ≈5⁎10−6 mm3/(Nm) with 18 wt.% Al2O3 addition. Pure NiCrAlY indeed suffers adhesive wear, whereas, on the composite coatings, the pull-out of some Al2O3 particles triggers the formation of a tribo-layer of smeared oxide fragments, which mediates the contact with the counterbody. At 400 °C and at 700 °C, all wear rates are levelled to ≈8⁎10−5 mm3/(Nm) and ≈2⁎10−5 mm3/(Nm), respectively. An oxide layer grows on the NiCrAlY matrix upon high-temperature exposure, resulting in a tribo-oxidation wear mechanism, which makes the addition of Al2O3 irrelevant. At 700 °C, coatings are further strengthened by partial healing of interlamellar defects and by fine-grained β-NiAl precipitating within the metal matrix.

Tribology of NiCrAlY+Al2O3 composite coatings by plasma spraying with hybrid feeding of dry powder+suspension / Bolelli, Giovanni; Candeli, Alessia; Lusvarghi, Luca; Ravaux, A.; Cazes, K.; Denoirjean, A.; Valette, S.; Chazelas, C.; Meillot, E.; Bianchi, L.. - In: WEAR. - ISSN 0043-1648. - ELETTRONICO. - 344-345:(2015), pp. 69-85. [10.1016/j.wear.2015.10.014]

Tribology of NiCrAlY+Al2O3 composite coatings by plasma spraying with hybrid feeding of dry powder+suspension

BOLELLI, Giovanni;CANDELI, ALESSIA;LUSVARGHI, Luca;
2015-01-01

Abstract

NiCrAlY layers containing different amounts of Al2O3 (0, 3, 6, 12, 18 wt.%) were deposited onto stainless steel substrates by a “hybrid” plasma spray process whereby the NiCrAlY powder was fed in dry form whilst fine Al2O3 powder, dispersed in ethanol, was injected through a suspension feeding system. The Al2O3 reinforcement, consisting of fine, rounded particles interspersed within larger NiCrAlY lamellae, only causes marginal changes in hardness, due to the limited particles-matrix cohesion. Nonetheless, at room temperature, ball-on-disk dry sliding wear rates against sintered Al2O3 counterparts decrease from ≈5⁎10−4 mm3/(Nm) for pure NiCrAlY to ≈5⁎10−6 mm3/(Nm) with 18 wt.% Al2O3 addition. Pure NiCrAlY indeed suffers adhesive wear, whereas, on the composite coatings, the pull-out of some Al2O3 particles triggers the formation of a tribo-layer of smeared oxide fragments, which mediates the contact with the counterbody. At 400 °C and at 700 °C, all wear rates are levelled to ≈8⁎10−5 mm3/(Nm) and ≈2⁎10−5 mm3/(Nm), respectively. An oxide layer grows on the NiCrAlY matrix upon high-temperature exposure, resulting in a tribo-oxidation wear mechanism, which makes the addition of Al2O3 irrelevant. At 700 °C, coatings are further strengthened by partial healing of interlamellar defects and by fine-grained β-NiAl precipitating within the metal matrix.
344-345
69
85
Tribology of NiCrAlY+Al2O3 composite coatings by plasma spraying with hybrid feeding of dry powder+suspension / Bolelli, Giovanni; Candeli, Alessia; Lusvarghi, Luca; Ravaux, A.; Cazes, K.; Denoirjean, A.; Valette, S.; Chazelas, C.; Meillot, E.; Bianchi, L.. - In: WEAR. - ISSN 0043-1648. - ELETTRONICO. - 344-345:(2015), pp. 69-85. [10.1016/j.wear.2015.10.014]
Bolelli, Giovanni; Candeli, Alessia; Lusvarghi, Luca; Ravaux, A.; Cazes, K.; Denoirjean, A.; Valette, S.; Chazelas, C.; Meillot, E.; Bianchi, L.
File in questo prodotto:
File Dimensione Formato  
Tribology of NiCrAlY+Al2O3 composite coatings by plasma spraying - Accepted Manuscript.pdf

Open Access dal 07/11/2017

Tipologia: Versione dell'autore revisionata e accettata per la pubblicazione
Dimensione 6.04 MB
Formato Adobe PDF
6.04 MB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/1073695
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 65
  • ???jsp.display-item.citation.isi??? 60
social impact