Tribological and mechanical behaviour of Cr3C2–NiCr thermally sprayed coatings after prolonged aging

• Cr3C2-25NiCr coating wear resistance increases after long aging above 300 °C.
• Monitoring crack nucleation and distribution through bending data analysis
• Residual stress release and microstructure evolution affect the cracking resistance.

Cr3C2–NiCr HVOF thermally sprayed coatings have been extensively applied on industrial components working at high temperature to improve their erosion, corrosion and oxidation resistance. In order to monitor the coating microstructural stability, a systematic investigation in the intermediate range of temperature 250–400 °C was carried out. Improved hardness and sliding wear resistance of the Cr3C2-based coatings was observed after long-term aging at temperature higher than 250 °C. However, the residual stress relaxation and a strengthening effect contributed to reduce the cracking resistance of the aged coatings, anticipating the onset of damage and crack opening to lower deflection levels during four-point bending tests.

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