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7457 |
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Thursday, May 05, 2022, Hall G2 11:20 AM Wear Protection I |
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Tribological behavior of HVAF-sprayed WC-based coatings with alternative binders |
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Luca Lusvarghi / University of Modena and Reggio Emilia , Italy Veronica Testa* / University of Modena and Reggio Emilia, Italia Giovanni Bolelli/ Università di Modena e Reggio Emilia, Italia Luca Lusvarghi / Università di Modena e Reggio Emilia, Italia Mohit Gupta/ University West, Sweden Kaveh Torkashvand/ University West, Sweden Shrikant Joshi/ University West, Sweden |
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Thermal spray WC-Co-based coatings represent the state-of-the-art for corrosion and wear protection of advanced mechanical components, used in many key industrial sectors, including aerospace, automotive, power generation, petrochemical and offshore. Since Co was defined a Critical Raw Material and according to the European Chemicals Agency may cause cancer, the present work focused on the deposition and characterization of safer and sustainable commercially WC-based hardmetal coatings with alternative binders containing no or very limited amount of cobalt. The studied compositions included WC-18%(Ni-16Mo-15Cr-5Fe-2Co), WC-15%(Fe-30Ni-28Cr-7Mo-1Cu) and WC-15%(Fe-20Cr-6Al) and they were deposited by High Velocity Air-Fuel (HVAF). Microstructure, tribological performances, under dry sliding, erosion, and abrasion wear conditions, and corrosion resistance in 3.5% (wt/vol) NaCl aqueous solution were evaluated and compared to standard WC-CoCr coatings as benchmarks. WC-NiMoCrFeCo coatings showed even better sliding wear resistance than the other compositions, exhibiting both the lowest value of COF against Al2O3 (?0.4) and the lowest specific wear rate after the ball on disc test (4·10-8 mm3/Nm), without splat delamination in the wear tracks. They also exhibit the best corrosion resistance in 3.5% NaCl solution. Abrasion wear resistance results confirm that WC-NiMoCrFeCo behaviour can be very close to WC-CoCr standard coatings. On the other hand, results on erosion resistance show a similar behaviour among the alternative binders compositions and in all cases, WC-CoCr hardmetal coatings showed a lower erosion rate. The studied compositions can represent a valid alternative to WC-CoCr selecting specific applications where the latter is routinely employed, despite the fact that an alternative composition which can outperform WC-CoCr state-of-the-art coatings in all the tested wear conditions has not been found, yet. In particular, WC-NiMoCrFeCo could be a very effective alternative in sliding wear applications. |