Fig. 1. Grain morphology of the Ni60 coating at different positions. (a) Macroscopic morphology; (b) bottom; (c) middle; (d) top

Fig. 2. Line scanning results of elements in cladding layer. (a) SEM image of coating; (b) line scanning result of coating; (c) SEM image of interface; (d) line scanning result of interface

Fig. 3. Surface scanning results of elements in cladding layer

Fig. 4. Friction coefficient under the action of solution with different pH values. (a) Friction coefficient - time curve; (b) average coefficient of friction

Fig. 5. Wear volume and three-dimensional morpHology under the action of solution with different pH values. (a) Wear volume; (b) pH=3; (c) pH=5; (d) pH=7; (e) pH=9; (f) pH=11

Fig. 6. Wear trace morphology and EDS of wear scar under different pH values. (a) pH=3; (b) pH=5; (c) pH=7; (d) pH=9; (e) pH=11