DescriptionThermally sprayed Cr3C2-25NiCr coatings are known for their good wear, corrosion and oxidation resistance. Under elevated temperature dry sliding contacts, the coatings are known to form an oxide based tribolayer which significantly decreases the coefficient of friction. Several commercial Cr3C2-based compositions exist that can be seen as alternatives to the conventional Cr3C2-25NiCr composition, e.g. Cr3C2-37WC-18NiCoCrFe and Cr3C2-50NiCrMoNb. These materials can potentially provide improved wear or corrosion protection. However, very limited information about their high temperature performance in sliding contacts can be found. In the current study, four commercial Cr3C2-based powders were used as feedstock materials to spray coatings. All coatings were produced with two spray processes: high velocity oxy-fuel (HVOF) and high velocity air-fuel (HVAF) spraying. The study shows that all coatings exhibit low coefficient of friction against an Al2O3 counterpart (between 0.35 and 0.48), while the Cr3C2-25NiCr coatings provided the lowest wear rate and coefficient of friction. Moreover, the HVAF sprayed Cr3C2-25NiCr provided improved wear resistance at high temperature sliding conditions compared to the HVOF sprayed counterpart. Structural analysis of the coatings revealed extensive carbide precipitation during the high temperature testing and sub-surface cracking of the HVOF sprayed coatings. Similar cracking behaviour was not observed on HVAF sprayed coatings. The coatings formed mainly a smooth and uniform oxide-based tribolayer on the wear surfaces and the collected wear debris consisted of micro- and nanometric crystalline oxide particles.
|Aikajakso||16 kesäk. 2016|
|Tapahtuman otsikko||NORDTRIB 2016: Nordic Symposium on Tribology|
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